Some companies track site statistics, such as how many times their content is accessed and by which types of Web browsers. User agent strings help identify the browser type.
Custom string to be appended to user agent string
The string you enter in this box is appended to the user agent string for the customized browser. You do not need to customize the user agent string unless you want to track the usage of your custom browser and you gather browser statistics from other Internet sites. Be aware that other companies that track site statistics will see the customized string.