A Raspberry Pi is a small SBC (single board computer) about the size of a credit card, although the Raspberry Pi zero is even smaller, about the size of a bourbon biscuit. You can use them for endless amounts of different things, your imagination is the limit. From the very normal like just using it as a little PC. To capturing images from the edge of the atmosphere and when it comes back down to earth it’ll let you know where its landed. What’s also great about Raspberry Pi’s and their many addons they are really cheap, it doesn’t cost the earth to start tinkering.