A pin header (or simply header) is a form of electrical connector. It consists of one or more rows of male pins typically spaced 2.54 millimetres (0.1in) apart, but sometimes 2 millimetres (0.079in) or 1.27 millimetres (0.05in) is used as well. The distance between pins is commonly referred as "pitch".
On single row pin headers the pins are bent alternating to one side or the other, on dual row pin headers the pins are simply bent outwards. If pin headers are optional, the PTH variant is often chosen for ease of manual assembly. Pin headers can be either straight or angled. The latter form is often used to connect two boards together. Pin headers are cost-effective due to their simplicity. Headers are often sold as long strips (typically 40 pins for the dual row versions) which can easily be broken off to the right number of pins