Ok, in the mobile world, it is important to understand that Google sometimes lies (Uhhh! Say it ain’t so!) Actually, all of the major search engines do it with mobile results - It is called 'transcoding.' In some cases, the search engines will want to rank a particular page in mobile results, but they know they shouldn’t because they can tell that it will be a bad mobile user experience. (Usually because the file size is too big, or the page has lots of mobile-unfriendly code like Flash or loads of JavaScript).

When this happens, the search engine will show the full search engine listing for the mobile-unfriendly page (like normal), but when you click on it, they will automatically take you to a temporary url that represents a ‘transcoded’ version of the page you requested, (rather than delivering you to the actual page listed in the search results). This temporary transcoded page actually lives on a subdomain hosted by the search engine, and shows a scraped version of the page you requested. The scrape usually just shows the text and small images of the page, but omits anything that might cause problems for a mobile browser; sometimes this can include background images, big images, animations, videos, iFrames, and heavy/complex code.

You Might Want Transcoding, but Probably Not

If you have totally ignored the mobile web, transcoding can be a good thing, because it allows you to rank in mobile results when you otherwise might be omitted. (Ranking with transcoding is better than not ranking at all). Unfortunately, none of the search engines do a stellar job with their transcoding. In Google, pages that are transcoded usually closely resemble the ‘text-only’ version of the page that Google keeps in its cache. In some cases though, the transcoding can really mess up a page, missing core navigation, breaking long pages into multiple pages at odd places, or cutting out important sections.

Remember that the search engine use of transcoded pages differs from phone to phone, so just because pages are not being automatically transcoded from search results on your phone does not mean that they are never being transcoded by the mobile search engines. The less sophisticated a mobile browser is, the more likely the search engine is to transcode a page; based on my experience, this is happening mostly on BlackBerry's and WindowsMobile devices. To see what a page looks like when Google transcodes it, there are two options:

1.) You can perform a search on a mobile phone, then click the ‘options’ button to the right of one of your results in the SERP, and then select ‘Mobile formatted.’ (Illustrated below)

2.) You can also put your url into Google’s tool, here: https://www.google.com/gwt/n? from your computer or your mobile phone.

The image below shows what Realtor.com looks like when it is transcoded by Google, and it is obviously not a great experience. You can see, in this instance, that two header images are missing, including the logo. It also turns the JavaScript navigation into text links that are a bit squished together, and hard to understand (Find a Home Home Finance Home & Garden). Last, since the transcoding software can't render JavaScript, it has been served an error message, telling it to turn on JavaScript.

Preventing Transcoding

If you are pretty confident in your mobile site rendering, you can include the ‘no-transform’ cache control in the headers of your template, and that will usually prevent your pages from being transcoded by the search engines, but it is not 100%. The good news is that with faster network connections and better mobile browsers, transcoding by the search engines is becoming much less common. The important take-away here, is to at least test to see what your pages look like when they are being transcoded (even if you have a no-transform cache control in place). In many cases, minor on-page code tweaks can make the transcoded experience much more user-friendly and palatable, improving your ability to reach the widest range of mobile customers, regardless of the phone they are searching from.