The Raspberry Pi is a series of credit card-sized single-board computers developed in the UK by the Raspberry Pi Foundation with the intention of promoting the teaching of basic computer science in schools.

A Raspberry Pi is a popular microcomputer. GPIO pins allow them to interface with various other electronics, and many Raspberry Pi "Hats" (electronic boards that physically mount to the top of a Raspberry Pi) extend them with capabilities they otherwise would not have. While Raspberry Pis are capable of outputting a PWM signal, the lack of dedicated on-board timer for that signal makes them poor at controlling servos directly. However a servo hat resolves that issue as well as making it easier to properly power your servo.