Another commonly used USB class is Communication Device Class. 

This class has broader capabilities than its most common use, which is tricking your PC software into thinking that your device is connected by an old-fashioned RS-232 port.

CDC devices are useful for projects that have a lot of legacy RS-232 code that your company doesn't want to have to rewrite. 

When your CDC device is installed, it will use a "Virtual COM Port," which can have a much higher effective Baud rate than your old (real) RS-232 port did. 

That's the good news.