Device detection analyzes the user agent (UA) string sent by the browser. UAs help identify what device is currently accessing the site. This can include browsers that are running email applications, app web views, operating systems and, most importantly, the device itself. UA strings are designated in the HTTP standard, which says that a UA is made up of multiple product tokens indicating the software and hardware characteristics of the device. Unfortunately, the rules involved in creating UAs aren’t strict. Browser makers and hardware manufacturers, who are responsible for naming the hardware in the UA, are free to format information about the device or the browser as they see fit. And with all the variations of devices, the task of accurately detecting devices is complicated and time consuming enough that simple hacks fail to do the job.