The ability to detect mobile devices is an important part of website and web application design. Over the last year, requests to sites from mobile devices such as tablets and smartphones have risen to almost 20% of total web traffic. As well as this, dozens of new devices with varying screen sizes, input methods and capabilities are released onto the market all the time. Keeping up with this diversity is a nessecery but difficult task for any organisation maintaining a presence on the web. A good solution is to use a Device Description Repository to detect mobile devices through the browser header and its User Agent. 51Degrees.mobi's professionally maintained device data makes this process easy to implement and stays current through automatic updates.