What is open-source software?

Instead of keeping code secret, open-source projects publish it under licences that allow others to study and improve it. The term was coined in 1998, building on the earlier free software movement led by Richard Stallman. Famous examples include the Linux operating system, the Firefox browser, the Android Open Source Project and the Python programming language. Much of the internet runs on open-source software, from web servers to databases. Platforms such as GitHub host many millions of open-source projects, developed by volunteers and companies around the world.