Incoming links: Pin header
Allows you to connect two adjacent pins of a pin header. Sometimes used as a hardware configuration interface!
Notably used to connect:
- pin headers
- breadboard holes
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!
Underside of a Raspberry Pi 2
. Source. At the top of this image we can clearly see how the usually pre-soldered pin header connectors go through the PCB and are soldered on both sides.