Mobile search engines have different bots and algorithms than those used for traditional web search. They evaluate your website as if it was being rendered on a mobile phone, and they rank results partially based on how well the page will render on the type of phone that submitted the query. If you look in your log files, you can even see that Googlebot-Mobile has different user agents that spoof different phones, like a Samsung phone, an iPhone or an Erickson phone. In some cases, different handsets will have different search results based on the evaluations that Google makes with the different user agents. The best thing you can do to improve your mobile SEO is to ensure that the mobile crawlers and user agents determine that your content will render well and load quickly on any mobile phone.
Since the mobile search engines are not as finely tuned as the traditional engines, they are still placing a heavy weight on a website’s mobile bounce rate, using the mobile visitors as barometers for how the website renders on their phone. This, again should reinforce the need for good mobile rendering. Here’s how you can improve mobile rankings and mobile rending of your website.
Basic mobile SEO & site architecture
One of the best things you can do to improve your mobile search results is follow traditional SEO best practices as closely as possible. While mobile bots and indexes are different from web search, things like title tags, heading tags and alt tags are still very important.
If you have done a good job on your traditional SEO, the first step is to create a secondary mobile style sheet for your traditional site, and call it “handheld.css.” This will allow you to format your existing pages for viewing on a mobile phone without having to create separate mobile content. It allows you to leverage the SEO value that you already have on your existing site without creating new pages. You can use the mobile style sheet to block things from being rendered using a “display:none” attribute in the stylesheet. Mobile phones (except iPhones) will automatically pull the “handheld” style sheet.
iPhones are bit different, and do not look for mobile “handheld” style sheets. To address this problem, you should duplicate your handheld sheet to create one that is specifically for the iPhone, and call it “iPhone.css.” Even though the iPhone is meant to render full web pages, research has shown that people still prefer mobile-formatted content on iPhones.
In some cases, mobile search engines will want to rank a traditional page, but deem it ill-suited for rendering on a mobile phone—sometimes even if it has a mobile-specific style sheet. In these cases, the mobile search engines will rank your traditional content, but “transcode” it for viewing on a mobile phone.
The transcoded version of the site is hosted on a temporary subdomain of on the search engine’s domain. In many cases, this provides an under-optimized user experience, because navigation is sometimes misplaced or broken, and single pages are broken into multiple pages for faster download. It can also be problematic for tracking the activity on your mobile site, and if anyone links to the content, the actual website may not get credit for the links. To address this concern, you must include a “no-transform” cache-control in the header for your traditional content. The no-transform designation in the cache control of the header should prevent the page from being transcoded.
The next step is to include a mobile site map. Google has a tool that can help you build a mobile sitemap. If you are using multiple markup languages, for instance XHTML and WML you should submit a separate mobile sitemap for each language that exists on the site, and include only the pages that will render in browsers that can read that type of code. Be sure to link to the mobile site map in your robots.txt file, just like you would for a traditional site map.
Submitting a mobile site map, adding the mobile style sheet and the no-transform tag should be enough to get the mobile search engines to start crawling and ranking your content. Mobile browsers are unsophisticated and networks can be slow. Another best practice to ensure that your traditional content will work on a mobile phone is to code in strict XHTML. This will give you the best chance of rendering well across the highest number of phones and browsers.
Advanced mobile SEO and site architecture
If the pages on your traditional site don’t use external style sheets, have a large file size, sloppy code or lots of multi-media content that could have trouble rendering on mobile phones, you might need to create mobile-specific content on a mobile subdomain or subdirectory (such as www.m.yoursite.com or www.yousite.com/m). This can be problematic for SEO, because it can split your links and traffic between two sets of similar pages. In terms of usability though, it may be worth the effort.
In your mobile-specific pages, you should also use a “handheld” style sheet and the no-transform designation, but you can also re-arrange the code so that it is more suited for mobile rendering and crawling. If you have extensive top navigation, the best practice is to move it to the bottom of the page, and include jump-links to it at the top of the page. The jump-links should link to major sections of the page, or could just link to your “main content,” “main navigation,” and “contact information.” These jump links will allow people to see more of the unique content above the fold, and will also minimize the amount of scrolling a user will have to do to find information on the page.
Ideally, mobile search engines would be able to see that you have both mobile and traditional content, and would choose to rank your mobile content above your traditional content in mobile search. Unfortunately that is not the case yet. In most cases, your mobile content is competing algorithmically against your traditional content in mobile search results, even when it is on a mobile subdirectory or mobile subdomain of your existing site. The mobile content is newer, has fewer links and sometimes, less content so it may be at an algorithmic disadvantage. That said, the next step is to link between the two versions of the site.
“Browser-detection and redirection, then self selection” is the mnemonic device that I like to use to describe how mobile and traditional websites should interact. Browser detection and re-direction is a process that looks to see what browser the web visitor is using to access the site; if a mobile browser is requesting the traditional site, a PHP script seamlessly redirects the user to the mobile site. If a traditional browser is requesting the mobile site, it seamlessly redirects them to the traditional site. This is especially handy if your traditional website out-ranks your mobile website in mobile search, but it can also be handy if your mobile site happens to our rank your traditional site in traditional search—which can happen.
The self-selection part of the rhyme simply refers to the idea that you should be linking between the traditional site and the mobile site with a text link. It is important that the link goes page-to-page rather than from any page on the traditional site to the home page of the mobile site, or vice versa. The link should be on the word “mobile” or “iPhone” if you have an iPhone-specific site. This is another great signal to give the search engines that the mobile content is optimized for mobile viewing, and should rank well in mobile search results. Links should always go from the traditional site to the mobile site and vice versa, to ensure that users are able to find exactly what they are looking for.
There are important notes about placing the self-selection link on your traditional sites. I highly recommend placing it in the very upper left hand corner of the traditional page. It should be a text link with appropriate anchor text that indicates mobility, but it should also include an image of a phone with good anchor text. This is because when traditional pages render on mobile phones, in some case the right site of the page is cut off or not displayed without side-to-side scrolling. If the button is placed in the upper right hand corner of the page or at the bottom of the page, it could be totally missed.
The phone image is necessary because in many cases, mobile phones with true-web-browsers will display traditional pages that are zoomed out to such a degree that normal size text-links become too small to read; the image helps catch the users eye. When people click the link, it is best to set a cookie, so that it tells the browser to always automatically redirect to the mobile version of the site. Not all mobile phones support cookies 100% but enough do that it is worth your time to do it.
Mobile platforms and software
If you are using a platform to “mobileize” your site, there are a couple things you need to look out for, as they can have a dramatic effect on mobile SEO. Most mobile platforms simply take the existing content on your traditional page and remove all complex code and media, leaving simply text and a minimal amount of images. This is basically the same as the “transcoding” that the search engines do, though with a proprietary platform it is more customizable. The first problem with these kinds of software is that if they are web based, they may include the mobile content on a subdomain of their main domain, rather than including it on your domain. This generally looks something like: www.yourdomain.theirdomain.com. In terms of SEO, that means that you are building up their domain rather than yours, and they have all control of the hosting. Any links, traffic or rankings that your mobile content accumulates are actually accredited to their domain rather than your own.
The next problem with mobilezing software is that frequently they will create temporary or poorly optimized file names, removing any SEO value from your site architecture or from links that use your URLs as anchor text. Even if the mobile content is on your own domain, the bad file names make it highly under-optimized. When your mobile content is on a mobile subdomain or subdirectory the best bet is to always mirror your traditional site architecture. This lets you take advantage of your previous efforts, including keywords in your file structure. It also makes it much easier for developers to link between the mobile and the traditional content, and to understand what is going on.
Again, you will need to submit a mobile site map and link it from your robots.txt file. If you are putting content on a mobile subdomain, you actually need to create a separate robots.txt file and place it and the mobile site map at the root directory of your mobile subdomain. It is fine to also link from the site map in root folder of the primary domain, but it is best to do both. With this strategy your mobile-specific content should be pared-down and optimized enough that it will out-rank the traditional site in searches on less sophisticated phones. In searches on smart phones, your traditional site is more likely to rank, but the browser detection and redirection should ensure that mobile users still get to the correct content. If you use this strategy, you actually provide a good user experience and the best chance of ranking well on the largest number of phones.
The reason I like this strategy so much is because it provides a lot of fall-back options, if something goes wrong. There are so many different mobile handsets and mobile browsers that it is hard to know that your web content will perform flawlessly. If browser-detection and redirection fails, you still have the self selection option. If that fails or is missed, you still have the handheld style sheet on the traditional content to improve its rendering on the mobile phone. This strategy works because it gives the mobile search engines lots of clues that your content is appropriate for ranking in mobile search. It also allows you to leverage the existing SEO power of your primary domain and still provide separate mobile experience when necessary.
Risks associated with mobile SEO
As you might have guessed, creating a copy of your website and putting it on a subdomain risks duplicate content issues. You would think that the mobile search engines would be smart enough to understand and interpret the duplication, but they can still get confused. If this is the case, your newer mobile content has little hope of ever outranking your older traditional content, even in mobile search. While the browser-detection and redirection should take care of this issue, you the duplicate content also risks bleeding a bit of the SEO value from the content on the traditional site.
If this is a concern, the best thing to do is try using the canonical tag, to push all the value from your mobile site back to your traditional site, and then rely on your browser detection and redirection to take care of the rest. The risk here is that you will hurt your rankings for searches on the less sophisticated phones, because you are pushing all the SEO value to the non-mobile content. The next option, if that doesn’t work, is use your robots.txt file to block the traditional crawler from reaching your mobile content, and potentially also blocking the mobile crawler from accessing your traditional content. This can be a bit risky, and should approached with caution, but should also improve the efficiency of both crawlers, keeping them focused on the content that is most important to them.
The other risk associated with any sophisticated mobile SEO strategy is that you get in trouble for the browser detection and redirection. Search engines are wary of automatic redirection because of its historical use as a spamming technique. The good news is that the search engines are very much in favor of good usability. Since the redirection is for the benefit of the user you should be OK, as long as you are providing the search engines with the same content as the visitors and you are not trying to do anything sneaky. This however, is another good reason to link directly from page-to-page, when you are creating the self selection links, because that is the best way to ensure that the two pages in the redirect scheme have similar content, so the redirect is less likely to be perceived as deceptive.
The future of mobile SEO
As you might have noticed, the mobile space and the development of mobile technology is moving along quite rapidly. It is important to understand that the search engines are scurrying to keep up, and they are still doing a lot of testing. Mobile algorithms get updates just like traditional web search algos, and in some cases, they can be significant.
Changes like the increased personalization of search results and the inclusion of real-time content like tweets and wall-posts is great for mobile search because it provides the user with information that they want quickly and easily. When you think about it, computers can be shared, but mobile phones rarely are, so the level of personalization in mobile search will continue to expand. The search engine can almost always safely assume that the person searching on your phone is you, and they can adapt results based on your previous search behavior, even when you are not actually logged in.
Mobile SEO can also be very focused on location, and though the search engines re not yet actively including your current GPS location in normal mobile web search, I think they will soon. Currently, to include GPS location data with your search query you actually have to set your location before you do your search. The potential for automatic inclusion of location information coupled with the personalization will make mobile search results even harder to anticipate and track. Mobile SEO will focus heavily on traffic as a measure of success for exactly this reason. The caveat is that if you are using mobile SEO to drive foot traffic to a store, people may get everything they need from the map, address, phone number and other information included in a mobile search result, and they may not even need to click through.
Applications are also altering mobile SEO. Mobile searchers are actually turning to mobile search applications instead of web search more and more. These include search engines like WikiTude, UrbanSpoon, RedLaser and Shazam. Downloadable search applications have different input mechanisms that can make them more fun, more interactive or more useful, and in many cases, the results tend to be more specialized and provide more information than a regular mobile web search.
It is also important to understand that applications are actually ranking in Google search results somewhat like a Universal result; so if your app is ranking well in the app store it could be pulled into a normal search result. With the launch of Google’s new mobile application marketplace Campfire, as well as the Android Marketplace and the AppStore, you can expect this to happen even more, both in mobile and traditional results. When you click on the link in the search results, it actually opens the AppStore on your phone or iTunes on your traditional computer, executing a command much like opening a PDF file in Adobe reader. Having applications that rank well in the application marketplaces is important for driving downloads, but it is can also be a strategy to push competitors down in traditional search results, like videos or images that rank in Universal results might do.
Opinions expressed in this article are those of the guest author and not necessarily Search Engine Land. Staff authors are listed here.