Twenty years ago, Netscape Communications was desperate. It was the darling of the first wave of internet companies for its ability to let you surf the web, but Microsoft had crushed its business prospects by giving away a web browser for free.
So Netscape did something that was radical for the time: On March 31, 1998, it gave away the source code behind its Netscape Communicator browser, the once-secret programming instructions that developers used to build the software. The project, called Mozilla, amounted to surrendering the crown jewels.

What exactly is open-source software?
Source code is software written in high-level programming languages that humans can understand. It’s often a closely guarded secret.
The open-source software movement embraced the idea that a project could progress faster with source code that anyone could see, change and distribute on their own. Interested people or companies could modify it for their own needs — “scratch your own itch” — and the openness means there’s more opportunity for people to spot bugs and offer solutions.
Early examples of open-source software — and its philosophical progenitor, the free-software movement — often began with no commercial ambitions at all. One of the most notable, the Linux core to a Unix-like operating system, began as a project by then-student Linus Torvalds.