You hear it talked about a lot... but have you ever wondered, what exactly is open source software?
Open source software is software with a specific license (MIT, GNU, etc) allowing it to be shared, reviewed, and modified by the public. The idea behind this type of licensing, is that you aren't keeping the source code proprietary, but rather openly collaborating with others who can both access and change the code. Traditionally, source code is owned by a company and only one team or person has access and legal rights to view and modify the proprietary code. But open source software is totally different. The authors of the software made it available to everyone, allowing people to change it, copy it, learn from it, or whatever else they want to do. It's a great tool for learning and spreading knowledge, and allows for the rapid advancement of the codebase, because the 'secrets' so to say, are out in the open for everyone to inspect and expand upon.
Open source software has many advantages that proprietary software does not. Since so many eyes are generally on a piece of software, bugs and mistakes are often found immediately- and since it's open and easily changed, those fixes can be implemented right away, as opposed to waiting for a nameless and faceless team in a different country to see comments on the customer service page and fix it. It's often also considered more stable, since it won't necessarily fall into disrepair if the original authors neglect it. People are always able to update or upgrade open source software, so it's helpful to have access to in long projects because individuals can ensure it stays up to date throughout the duration. It also allows small teams and startups to advance their business or idea in a much more rapid way as they are able to take advantage of public code written by other developers.
Much of the early internet was built on open source software and it's still a huge piece of the web. It's a great tool for learning, and a great example of the awesome effects of collaboration and idea-sharing. It is a big driver of many technological advancements, and will always have its place on the web.