Just about all electronics use TTL serial for debugging, bootloading, programming, serial output, etc. But it's rare for a computer to have a serial port anymore. This is a USB to TTL serial cable, with a FTDI FT232RL usb/serial chip embedded in the head. It has a 6-pin socket...
If you've ever struggled to use a solderless breadboard with an Arduino, you understand how frustrating it can be!
Note: These use genuine FTDI chips, either we purchase them or they are manufactured to our specifications with the requirement of genuine FTDI chips 10/22/14 - read more.