Search engines are limited in how they crawl the web and interpret content to retrieve and display in the results. In this section of the guide, we'll focus on the specific technical aspects of building (or modifying) web pages so they're optimally structured for search engines and human visitors. This is an excellent part of the guide to share with your programmers, information architects, and designers, so that all parties involved in a site's construction can plan and develop a search-engine friendly site.
In order to be listed in the search engines, your content - the material available to visitors of your site - must be in HTML text format. Images, Flash files, Java applets, and other non-text content is virtually invisible to search engine spiders, despite advances in crawling technology. The easiest way to ensure that the words and phrases you display to your visitors are visible to search engines is to place it in the HTML text on the page. However, more advanced methods are available for those who demand greater formatting or visual display styles:
| ||
| ||
Now let's double-check some stuff
Most sites do not have significant problems with indexable content, but double-checking is worthwhile. By using tools like Google's cache, SEO-browser.com, the MozBar or Yellowpipe you can see what elements of your content are visible and indexable to the engines.
Whoa! That's what we look like?
Using the Google cache feature, we're able to see that to a search engine, JugglingPandas.com's homepage is simply a link to another page. This is bad because it makes it difficult to interpret relevancy.
That’s a lot of monkeys, and just headline text?
Hey, where did the fun go?
Uh oh... via Google cache, we can see that the page is a barren wasteland. There's not even text telling us that the page contains the Axe Battling Monkeys. The site is entirely built in Flash, but sadly, this means that search engines cannot index any of the text content, or even the links to the individual games.
If you're curious about exactly what terms and phrases search engines can see on a webpage, we have a nifty tool called "Term Extractor" that will display words and phrases ordered by frequency. However, it's wise to not only check for text content but to also use a tool like SEO Browser to double-check that the pages you're building are visible to the engines. It's very hard to rank if you don't even appear in the search engine keyword databases.
Search engines need to see content in order to list pages in their massive keyword-based indices. They also need to have access to a crawlable link structure - one that lets their spiders browse the pathways of a website - in order to find all of the pages on a website. Hundreds of thousands of sites make the critical mistake of hiding or obfuscating their navigation in ways that search engines cannot access, thus impacting their ability to get pages listed in the search engines' indices. Below, we've illustrated how this problem can happen:
In the example above, Google's spider has reached page "A" and sees links to pages "B" and "E". However, even though C and D might be important pages on the site, the spider has no way to reach them (or even know they exist) because no direct, crawlable links point to those pages. As far as Google is concerned, they might as well not exist - great content, good keyword targeting, and smart marketing won't make any difference at all if the spiders can't reach those pages in the first place.
In the above illustration, the "<a" tag indicates the start of a link. Link tags can contain images, text, or other objects, all of which provide a clickable area on the page that users can engage to move to another page. This is the original navigational element of the Internet - "hyperlinks". The link referral location tells the browser (and the search engines) where the link points to. In this example, the URL http://www.jonwye.com is referenced. Next, the visible portion of the link for visitors, called "anchor text" in the SEO world, describes the page the link points to. The page pointed to is about custom belts, made by my friend from Washington D.C., Jon Wye, so I've used the anchor text "Jon Wye's Custom Designed Belts". The </a> tag closes the link, so that elements later on in the page will not have the link attribute applied to them.
This is the most basic format of a link - and it is eminently understandable to the search engines. The spiders know that they should add this link to the engines link graph of the web, use it to calculate query-independent variables (like Google's PageRank), and follow it to index the contents of the referenced page.
Links in submission-required forms
Forms can include something as basic as a drop down menu or as complex as a full-blown survey. In either case, search spiders will not attempt to "submit" forms and thus, any content or links that would be accessible via a form are invisible to the engines.
Links in un-parseable Javascript
If you use Javascript for links, you may find that search engines either do not crawl or give very little weight to the links embedded within. Standard HTML links should replace Javascript (or accompany it) on any page where you'd like spiders to crawl.
Links pointing to pages blocked by the meta robots tag or robots.txt
The Meta Robots tag and the Robots.txt file (full description here) both allow a site owner to restrict spider access to a page. Just be warned that many a webmaster has unintentionally used these directives as an attempt to block access by rogue bots, only to discover that search engines cease their crawl.
Links in frames or I-frames
Technically, links in both frames and I-Frames are crawlable, but both present structural issues for the engines in terms of organization and following. Unless you're an advanced user with a good technical understanding of how search engines index and follow links in frames, it's best to stay away from them.
Links only accessible through search
Although this relates directly to the above warning on forms, it's such a common problem that it bears mentioning. Spiders will not attempt to perform searches to find content, and thus, it's estimated that millions of pages are hidden behind completely inaccessible walls, doomed to anonymity until a spidered page links to it.
Links in flash, java, or other plug-ins
The links embedded inside the Panda site (from our above example) is a perfect illustration of this phenomenon. Although dozens of pandas are listed and linked to on the Panda page, no spider can reach them through the site's link structure, rendering them invisible to the engines (and un-retrievable by searchers performing a query).
Links on pages with many hundreds or thousands of links
Search engines tend to only crawl about 100 links on any given page. This loose restriction is necessary to keep down on spam and conserve rankings.
Rel="nofollow" can be used with the following syntax:
<a href=http://www.seomoz.org rel="nofollow">Lousy Punks!</a>Links can have lots of attributes applied to them, but the engines ignore nearly all of these, with the important exception of the rel="nofollow" tag. In the example above, by adding the rel=nofollow attribute to the link tag, we've told the search engines that we, the site owners, do not want this link to be interpreted as the normal, "editorial vote." Nofollow came about as a method to help stop automated blog comment, guestbook, and link injection spam (read more about the launch here), but has morphed over time into a way of telling the engines to discount any link value that would ordinarily be passed. Links tagged with nofollow are interpreted slightly differently by each of the engines. You can read more about the affect of this and PageRank sculpting on this blog post.
nofollowed links carry no weight or impact and are interpreted as HTML text (as though the link did not exist). Google's representatives have said that they will not count those links in their link graph of the web at all. Yahoo! & BingBoth of these engines say that nofollowed links do not impact search results or rankings, but may be used by their crawlers as a way to discover new pages. That is to say that while they "may" follow the links, they will not count them as a method for positively impacting rankings. Ask.comAsk is unique in its position, claiming that nofollowed links will not be treated any differently than any other kind of link. It is Ask's public position that their algorithms (based on local, rather than global popularity) are already immune to most of the problems that nofollow is intended to solve. | ||
Keywords are fundamental to the search process - they are the building blocks of language and of search. In fact, the entire science of information retrieval (including web-based search engines like Google) is based on keywords. As the engines crawl and index the contents of pages around the web, they keep track of those pages in keyword-based indices. Thus, rather than storing 25 billion web pages all in one database (which would get pretty big), the engines have millions and millions of smaller databases, each centered on a particular keyword term or phrase. This makes it much faster for the engines to retrieve the data they need in a mere fraction of a second.
Obviously, if you want your page to have a chance of being listed in the search results for "dog," it's extremely wise to make sure the word "dog" is part of the indexable content of your document.
Keywords also dominate our search intent and interaction with the engines. For example, a common search query pattern might go something like this:
When a search is performed, the engine knows which pages to retrieve based on the words entered into the search box. Other data, such as the order of the words ("tanks shooting" vs. "shootingtanks"), spelling, punctuation, and capitalization of those terms provide additional information that the engines can use to help retrieve the right pages and rank them.
For obvious reasons, search engines measure the ways keywords are used on pages to help determine the "relevance" of a particular document to a query. One of the best ways to "optimize" a page's rankings is, therefore, to ensure that keywords are prominently used in titles, text, and meta data.
The map graphic to the left shows the relevance of the broad termbooks to the specific title, Tale of Two Cities. Notice that while there are a lot of results (size of country) for the broad term, there is a lot less results and thus competition for the specific result.
Whenever the topic of keyword usage and search engines come together, a natural tendency is to use the phrase "keyword density". This is tragic. Keyword density is, without question, NOT a part of modern web search engine ranking algorithms for the simple reason that it provides far worse results than many other, more advanced methods of keyword analysis. Rather than cover this logical fallacy in depth in this guide, we'll simply reference Dr. Edel Garcia's seminal work on the topic - The Keyword Density of Non-Sense.
The notion of keyword density value predates all commercial search engines and the Internet and can hardly be considered an information retrieval concept. What is worse, keyword density plays no role on how commercial search engines process text, index documents, or assign weights to terms. Why then do many optimizers still believe in keyword density values? The answer is simple: misinformation.
Dr. Garcia's background in information retrieval and his mathematical proofs should debunk any notion that keyword density can be used to help "optimize" a page for better rankings. However, this same document illustrates the unfortunate truth about keyword optimization - without access to a global index of web pages (to calculate term weight) and a representative corpus of the Internet's collected documents (to help build a semantic library), we have little chance to create formulas that would be helpful for true optimization.
That said, keyword usage and targeting are only a small part of the search engines' ranking algorithms, and we can still leverage some effective "best practices" for keyword usage to help make pages that are very close to "optimized." Here at SEOmoz, we engage in a lot of testing and get to see a huge number of search results and shifts based on keyword usage tactics. When working with one of your own sites, this is the process we recommend:
- Use the keyword in the title tag at least once, and possibly twice (or as a variation) if it makes sense and sounds good (this is subjective, but necessary). Try to keep the keyword as close to the beginning of the title tag as possible. More detail on title tags follows later in this section.
- Once in the H1 header tag of the page.
- At least 3X in the body copy on the page (sometimes a few more times if there's a lot of text content). You may find additional value in adding the keyword more than 3X, but in our experience, adding more instances of a term or phrase tends to have little to no impact on rankings.
- At least once in bold. You can use either the <strong> or <b> tag, as search engines consider them equivalent.
- At least once in the alt attribute of an image on the page. This not only helps with web search, but also image search, which can occasionally bring valuable traffic.
- Once in the URL. Additional rules for URLs and keywords are discussed later on in this section.
- At least once (sometimes 2X when it makes sense) in the meta description tag. Note that the meta description tag does NOT get used by the engines for rankings, but rather helps to attract clicks by searchers from the results page (as it is the "snippet" of text used by the search engines).
- Generally not in link anchor text on the page itself that points to other pages on your site or different domains (this is a bit complex - see this blog post for details).
Keyword Density Myth ExampleIf two documents, D1 and D2, consist of 1000 terms (l = 1000) and repeat a term 20 times (tf = 20), then a keyword density analyzer will tell you that for both documents Keyword Density (KD) KD = 20/1000 = 0.020 (or 2%) for that term. Identical values are obtained when tf = 10 and l = 500. Evidently, a keyword density analyzer does not establish which document is more relevant. A density analysis or keyword density ratio tells us nothing about:
The Conclusion:Keyword density is divorced from content, quality, semantics, and relevancy. | ||
What should optimal page density look like then? An optimal page for the phrase “running shoes” would thus look something like:
You can read more information about On-Page Optimization at this post.
The title tag of any page appears at the top of Internet browsing software, but this location has been noted to receive a relatively small amount of attention from users, making it the least important of the three.
Using keywords in the title tag means that search engines will "bold" (or highlight) those terms in the search results when a user has performed a query with those terms. This helps garner a greater visibility and a higher click-through rate.
The final important reason to create descriptive, keyword-laden title tags is for ranking at the search engines. The above screenshot comes from SEOmoz's survey of 37 influential thought leaders and practitioners in the SEO industry on the search engine ranking factors. In that survey, 35 of the 37 participants said that keyword use in the title tag was the most important place to use keywords to achieve high rankings.
The title element of a page is meant to be an accurate, concise description of a page's content. It creates value in three specific areas (covered to the left) and is critical to both user experience and search engine optimization.
As title tags are such an important part of search engine optimization, following best practices for title tag creation makes for terrific low-hanging SEO fruit. The recommendations below cover the critical parts of optimizing title tags for search engine and usability goals:
Be mindful of length
70 characters is the maximum amount that will display in the search results (the engines will show an ellipsis - "..." to indicate when a title tag has been cut off), and sticking to this limit is generally wise. However, if you're targeting multiple keywords (or an especially long keyword phrase) and having them in the title tag is essential to ranking, it may be advisable to go longer.
Place important keywords close to the front
The closer to the start of the title tag your keywords are, the more helpful they'll be for ranking and the more likely a user will be to click them in the search results (at least, according to SEOmoz's testing and experience).
Leverage branding
At SEOmoz, we love to start every title tag with a brand name mention, as these help to increase brand awareness, and create a higher click-through rate for people who like and are familiar with a brand. Many SEO firms recommend using the brand name at the end of a title tag instead, and there are times when this can be a better approach - think about what matters to your site (or your client's site) and how strong the brand is.
Consider readability and emotional impact
Creating a compelling title tag will pull in more visits from the search results and can help to invest visitors in your site. Thus, it's important to not only think about optimization and keyword usage, but the entire user experience. The title tag is a new visitor's first interaction with your brand and should convey the most positive impression possible.
Best Practices for Title TagsMeta tags were originally intended to provide a proxy for information about a website's content. Each of the basic meta tags are listed below, along with a description of their use.
The Meta Robots tag can be used to control search engine spider activity (for all of the major engines) on a page level. There are several ways to use meta robots to control how search engines treat a page:
- Index/NoIndex tells the engines whether the page should be crawled and kept in the engines' index for retrieval. If you opt to use "noindex", the page will be excluded from the engines. By default, search engines assume they can index all pages, so using the "index" value is generally unnecessary.
- Follow/NoFollow tells the engines whether links on the page should be crawled. If you elect to employ "nofollow," the engines will disregard the links on the page both for discovery and ranking purposes. By default, all pages are assumed to have the "follow" attribute.
- Noarchive is used to restrict search engines from saving a cached copy of the page. By default, the engines will maintain visible copies of all pages they indexed, accessible to searchers through the "cached" link in the search results.
- Nosnippet informs the engines that they should refrain from displaying a descriptive block of text next to the page's title and URL in the search results.
- NoODP is a specialized tag telling the engines not to grab a descriptive snippet about a page from the Open Directory Project (DMOZ) for display in the search results.
- NoYDir, like NoODP, is specific to Yahoo!, informing that engine not to use the Yahoo! Directory description of a page/site in the search results.
The meta description tag exists as a short description of a page's content. Search engines do not use the keywords or phrases in this tag for rankings, but meta descriptions are the primary source for the snippet of text displayed beneath a listing in the results.
The meta description tag serves the function of advertising copy, drawing readers to your site from the results and thus, is an extremely important part of search marketing. Crafting a readable, compelling description using important keywords (notice how Google "bolds" the searched keywords in the description) can draw a much higher click-through rate of searchers to your page.
Meta descriptions can be any length, but search engines generally will cut snippets longer than 160 characters (as in the Balboa Park example to the right), so it's generally wise to stay in these limits.
Meta Keywords
The meta keywords tag had value at one time, but is no longer valuable or important to search engine optimization. For more on the history and a full account of why meta keywords has fallen in disuse, read Meta Keywords Tag 101 from SearchEngineLand.
Meta refresh, meta revisit-after, meta content type, etc.
Although these tags can have uses for search engine optimization, they are less critical to the process, and so I'll leave them to John Mueller of Google's Webmaster Central division to answer in greater detail - Meta Tags & Web Search.
URLs, the web address for a particular document, are of great value from a search perspective. They appear in multiple important locations.
Above, the green text shows the url for SEOmoz’s Web 2.0 awards. Since search engines display URLs in the results, they can impact clickthrough and visibility. URLs are also used in ranking documents, and those pages whose names include the queried search terms receive some benefit from proper, descriptive use of keywords.
URLs make an appearance in the web browser's address bar, and while this generally has little impact on search engines, poor URL structure and design can result in negative user experiences.
The URL above is used as the link anchor text pointing to the referenced page in this blog post.
Employ Empathy
Place yourself in the mind of a user and look at your URL. If you can easily and accurately predict the content you'd expect to find on the page, your URLs are appropriately descriptive. You don't need to spell out every last detail in the URL, but a rough idea is a good starting point.
Shorter is better
While a descriptive URL is important, minimizing length and trailing slashes will make your URLs easier to copy and paste (into emails, blog posts, text messages, etc) and will be fully visible in the search results.
Keyword use is important (but overuse is dangerous)
If your page is targeting a specific term or phrase, make sure to include it in the URL. However, don't go overboard by trying to stuff in multiple keywords for SEO purposes - overuse will result in less usable URLs and can trip spam filters (from email clients, search engines, and even people!).
Go static
With technologies like mod_rewrite for Apache and ISAPI_rewrite for Microsoft, there's no excuse not to create simple, static URLs. Even single dynamic parameters in a URL can result in lower overall ranking and indexing (SEOmoz itself switched from dynamic URLs - e.g. www.seomoz-.org/blog?id=123, to static URLS - e.g. www.seomoz.org/blog/11-best-practices-for-urls, in 2007 and saw a 15% rise in search traffic over the following 6 weeks).
Choose descriptives whenever possible
Rather than selecting numbers or meaningless figures to categorize information, use real words. For example, a URL like www.thestore.com/hardware/screwdrivers is far more usable and valuable than www.thestore.com/cat33/item4326.
Use hyphens to separate words
Not all of the search engines accurately interpret separators like underscore "_," plus "+," or space "%20," so use the hyphen "-" character to separate words in a URL, as in the SEOmoz 11 Best Practices for URLs example above.
Canonicalization can be a challenging concept to understand (and hard to pronounce - "ca-non-ick-cull-eye-zay-shun"), but it's essential to creating an optimized website. The fundamental problems stem from multiple uses for a single piece of writing - a paragraph or, more often, an entire page of content will appear in multiple locations on a website, or even on multiple websites. For search engines, this presents a conundrum - which version of this content should they show to searchers? In SEO circles, this issue often referred to as duplicate content - described in greater detail here.
The engines are picky about duplicate versions of a single piece of material. To provide the best searcher experience, they will rarely show multiple, duplicate pieces of content and thus, are forced to choose which version is most likely to be the original (or best).
Canonicalization is the practice of organizing your content in such a way that every unique piece has one and only one URL. By following this process, you can ensure that the search engines will find a singular version of your content and assign it the highest achievable rankings based on your domain strength, trust, relevance, and other factors. If you leave multiple versions of content on a website (or websites), you might end up with a scenario like that to the right.
If, instead, the site owner took those three pages and 301-redirected them, the search engines would have only one, stronger page to show in the listings from that site:
You say you want another option though?
A different option from the search engines, called the "Canonical URL Tag" is another way to reduce instances of duplicate content on a single site and canonicalize to an individual URL. (This can also be used from one URL on one domain to a different URL on a different domain.)
The tag is part of the HTML header on a web page, the same section you'd find the Title elementand Meta Description tag. This simply uses a new rel parameter.
<link rel=”canonical” href=”http://www.seomoz.org/blog”/>This would tell Yahoo!, Bing & Google that the page in question should be treated as though it were a copy of the URL www.seomoz.org/blog and that all of the link & content metrics the engines apply should technically flow back to that URL.The Canonical URL tag attribute is similar in many ways to a 301 redirect from an SEO perspective. In essence, you're telling the engines that multiple pages should be considered as one (which a 301 does), without actually redirecting visitors to the new URL (often saving your development staff considerable heartache).
How we do it
SEOmoz has worked on several campaigns where two versions of every content page existed in both a standard, web version and a print-friendly version. In one instance, the publisher's own site linked to both versions, and many external links pointed to both as well (this is a common phenomenon, as bloggers & social media types like to link to print-friendly versions to avoid advertising). We worked to individually 301 re-direct all of the print-friendly versions of the content back to the originals and created a CSS option to show the page in printer-friendly format (on the same URL). This resulted in a boost of more than 20% in search engine traffic within 60 days. Not bad for a project that only required an hour to identify and a few clever rules in the htaccess file to fix.
How scrapers like your rankings
Unfortunately, the web is filled with hundreds of thousands (if not millions) of unscrupulous websites whose business and traffic models depend on plucking the content of other sites and re-using them (sometimes in strangely modified ways) on their own domains. This practice of fetching your content and re-publishing is called "scraping," and the scrapers make remarkably good earnings by outranking sites for their own content and displaying ads (ironically, often Google's own AdSense program).
When you publish content in any type of feed format - RSS/XML/etc - make sure to ping the major blogging/tracking services (like Google, Technorati, Yahoo!, etc.). You can find instructions for how to ping services like Google and Technorati directly from their sites, or use a service like Pingomatic to automate the process. If your publishing software is custom-built, it's typically wise for the developer(s) to include auto-pinging upon publishing.
Next, you can use the scrapers' laziness against them. Most of the scrapers on the web will re-publish content without editing, and thus, by including links back to your site, and the specific post you've authored, you can ensure that the search engines see most of the copies linking back to you (indicating that your source is probably the originator). To do this, you'll need to use absolute, rather that relative links in your internal linking structure. Thus, rather than linking to your home page using:
<a href="../>Home</a>You would instead use:<a href="http://www.seomoz.org">Home</a>This way, when a scraper picks up and copies the content, the link remains pointing to your site.
There are more advanced ways to protect against scraping, and for WordPress users Joost de Valk has a useful plugin, but none of them are entirely foolproof. You should expect that the more popular and visible your site gets, the more often you'll find your content scraped and re-published. Many times, you can ignore this problem, but if it gets very severe, and you find the scrapers taking away your rankings and traffic, you may consider using a legal process called a DMCA takedown. Luckily, SEOmoz's own in-house counsel, Sarah Bird, has authored a brilliant piece to help solve just this problem -Four Ways to Enforce Your Copyright: What to Do When Your Online Content is Being Stolen.
No comments:
Post a Comment
Please feel free to contact or comment the article