In Europe and Asia, more and more people are using their mobile phone as a primary mode of information gathering. They're surfing the Web, sending messages, making purchases, exploring maps and even listening to music.

So the obvious question is this: Is your Web site mobile-compliant?

Below is a checklist to help you discover whether your content is being read by mobile phones. You can also download a PDF version here.

1. How large are your pages?
Pages intended to be seen on a mobile device should contain as little extraneous information as possible while still keeping all of the integral content intact. Ideally, a page should be less than 1120k. Pages that require lots of scrolling on a desktop computer could be unreadable on a mobile device.

2. Are you delivering content for the correct screen size?
Most mobile devices are 200 pixels wide by 300 pixels tall or less. (The current exception is the iPhone, which offers 320 px in width x 480 px in height.) If your site has images that are larger or screen content that requires scrolling, it will not render correctly (or at all in many cases) on a mobile device.

3. How long will your site take to load on a mobile device?
The quicker the better, since many people pay based on how much data they are using.

4. Does your Web site use frames?
Most mobile devices will not support them. (See this site for more information about frames.)

5. Does your site use an XHTML mobile profile?
The best markup language for a mobile device is XHTML-MP. You may need to re-encode your site to display as both a Web version and as a mobile version.

6. Do you have the right MIME types?
MIME types are sent with Web documents to help browsers interpret the information for viewing. Mobile phone browsers require different MIME types than browsers used with desktop and laptop computers. For XHTML-MP, the MIME type is application/vnd.wap.xhtml+xml or application/xhtml+xml.

7. Does your site require forms?
If you require a user to fill out forms before using the site and if his/her mobile device either doesn’t display those forms correctly or won’t allow them to be filled out, you won’t reach most of your potential mobile audience.

8. Do you have the correct character encoding?
There are lots of ways to encode a Web site, but only a specific way will work so that pages render correctly on a mobile device. The UTF-8 character set should almost always be used.

9. Does your site use pop-up windows and/or floating windows?
Many Web sites continue to use pop-up windows for advertising. Many also have floating windows on top of their Web sites and they require a user to close the window before s/he can see the content behind it. Neither pop-ups nor floating windows will work on a mobile device, as mobile browsers typically do not support them.

10. Is your site image-heavy?
Unless you reencode your site to deliver pictures very easily or you make your site readable without images, it could be costly and difficult for users to access your site from their mobile device. If you do leave images as is, it is best to always specify within the code the width and height as attributes.

11. Are you using embedded objects?
The code to embed an object, such as a YouTube video, is not always supported by mobile devices.

12. Does your site require javascript?
Although many mobile devices claim to support javascript, many actually do not. Currently, javascript cannot be read on the bulk of mobile phones - however lots of users do not realize that until they’ve already spent several minutes trying to download a video or series of images.

13. Does your site currently redirect?
Sites that redirect automatically can cost users minutes and download allotments as they are navigated to another site.

14. Does your site offer cache control headers?
Cached information will dramatically reduce the amount of time it takes to load and reload pages - and will eventually cut down on user-incurred costs.

15. Are you helping your users navigate?
Does your main Web site offer an explanation of mobile access to your content, how your mobile version can be used and which carriers support (or don’t) your content? If you want to increase traffic via mobile devices, your main Web site should offer as much clear explanation as possible for users wanting to access your content when away from their computers.

[1] Gartner, Inc. research from Q4 2007: http://www.gartner.com. [2] As specified by the W3C mobileOK Basic Tests 1.0 document, 30 November 2007: http://www.w3.org/TR/mobileOK-basic10-tests.