The future of the Internet passes through navigation from portable or mobile devices, and the major search engines are already working on some special editions of the same information organized in a way different from the usual results.

What browsers are beginning to use specific search sites for mobile? For the main already have acquired, and even some of them have an option to only show results tailored to mobile devices:

Google Mobile: has an option to filter content for mobile phones only.
Live Search Mobile
Technorati Mobile
Yahoo! Mobile: has an option to filter content for mobile phones only.
In addition, recently there domains. MOBI, which require the use of a concrete specification and follow the restrictive rules as to how to display the contents. So it is advisable to use such domains in positioning a mobile site.

15.1. XHTML Mobile

One of the first items to consider is that the format of the site may not be the same as normal. There is a thought XHTML for mobile terminals in which no common elements are allowed in other versions. To learn all about these kinds of sites you can visit dev.mobi, the site developer.

Some of these limitations are:

Screen Width: 120 pixels minimum
XHTML Basic 1.1 (application / xhtml + xml)
Encoding: UTF-8
Image Format: JPEG and GIF 89a
Max Page: 20 kilobytes
256 colors (minimum)
CSS 1 and 2
HTTP/1.0 and HTTP/1.1
Not allow scripts
This case is very important that the website validates correctly, because even desktop browsers allow you to bypass some of these rules, mobile browsers are much stricter.

To verify that a site is compatible and to see how it looks in some mobile terminals is recommended to use the validator ready.mobi.

15.2. High search engine

As said before, there are search engines that support this format and completely and, therefore, allow enlist mobile web sites:

High on Google
It must be done from their tools and using a Mobile Sitemap.
Added on Yahoo!
Can be done two ways: by entering the address of the website and allowing the robot to index or via feeds or Mobile Sitemaps. In both cases, Yahoo! offers a form to the high mobile site.
15.3. robots.txt

One of the most important issues that face you'd have to have a mobile site is to generate duplicate content, because if not you will find that you prevent search bots indexed by default, the site at all possible sites result. To prevent this from happening, you have a robots.txt file to tell the policies that only allow indexing by specific mobile robots.


User-Agent: *
Disallow: /
User-Agent: Googlebot-Mobile
User-Agent: YahooSeeker/M1A1-R2D2
Allow:

By the time the search engines that have agents are:

Google: Googlebot-Mobile
Yahoo!: YahooSeeker/M1A1-R2D2