Four years since it first went on sale to eager developers, the credit card-sized Raspberry Pi computer has sold an impressive 10 million units.

It remains the UK’s best-selling computer ever—and a reminder that you don’t have to be a Silicon Valley heavyweight to create a successful slice of tech.

Dreamed up by the Raspberry Pi Foundation charity as a way to bring computer science and coding back into schools, the Welsh-built Raspberry Pi has not only found its way into thousands of schools across the globe but has also taken on a life of its own as a hobbyist device.