Ciro Santilli @cirosantilli 37

Allows you to connect two adjacent pins of a pin header. Sometimes used as a hardware configuration interface!

Notably used to connect:

You can buy large sets of them in combitation of male/male, male/female, female/female. Male/male is perhaps the most important

These often come pre-soldered on devboards, e.g. and allow for easy access to GPIO pins. E.g. they're present on the Raspberry Pi 2.

Why would someone ever sell a devboard without them pre-soldered!