If you don’t know what Raspberry Pi 4 is, then you have landed in the right place.
Raspberry Pi is a series of small single-board computers developed by the Raspberry Pi Foundation to promote the teaching of basic computer science in schools and developing countries. The original model became far more popular than anticipated, selling outside its target market for uses such as robotics. It does not include peripherals (such as keyboards and mice) and cases. However, some accessories are packed in several official and unofficial bundles.