The fast growth in the mobile phone use has changed the way the web worked. In early days people use desktop or laptop for their day to day work. However now this has been changed a lot and people started using mobile phone for their internet usage. It became mandatory for the web analytics solution providers to provide the report based on the traffic from mobile devices and non mobile devices.
How the mobile device traffics are identified:
The user-agent string of the browser is the key element to identify whether the traffic is from mobile device or non mobile device. Mobile devices (it can be any brand or model) has its own unique user-agent string defined. In order to identify the device the user-agent string must be compared with mobile device database such as www.wurfl.com.
Even though user-agent helps to find the mobile device and non mobile device traffic with the help of user-agent string we can not measure the unique users. There are many ways to identify the unique users but I personally feel all the solutions are not 100% accurate.