Refers to something – typically software – that can be modified and shared because of its publicly accessible design. Open-source programs, or applications, can be developed collaboratively and changed at the discretion of users and programmers (other than those who created it) to add features or fix code. Conversely, proprietary, or closed-source, software consists of source code that can be modified only by the party that created it.

Though still used commonly to describe publicly accessible software, “open-source” has a broader definition today, referring also to products, initiatives, and projects that embrace the principles of collaboration, community-oriented development, open exchange, and rapid prototyping.