What is free software?

What it means

The Free Software Foundation defines free software by four freedoms: to run the program for any purpose, to study how it works and change it, to share copies, and to share your modified versions. The second and fourth require access to the source code. Free programs can be sold.

Most free software is also open source. The two terms differ in emphasis: free software treats the freedoms as a matter of principle, and open source stresses the practical benefits of shared development. Linux and the GNU tools are common examples.

Some free licenses are copyleft. The GPL is the best-known one: if you distribute a modified version, you must release it under the same license and make its source code available.

Why it matters to a business

• Run it however you need: the license allows any purpose, with your own team or a partner doing the work.
• No vendor can withdraw it: the license cannot be taken back from the copies you have, and if the original developers stop, anyone may carry the code on.
• Internal use: running free software inside your own company generally carries no extra obligation. The AGPL is the main exception: if you change an AGPL program and let outside users reach it over a network, you must offer them your changes.
• Distribution: if you give or sell a modified copyleft program to others, you must share your changes under the same license.

How this shows up in our work

Much of what we run and build for clients is free and open-source software: Linux servers on Ubuntu, Debian and RHEL-family systems, Proxmox VE, Ceph, Docker, OPNsense and FreePBX. We run Proxmox and Ceph for our own infrastructure, and we maintain public open-source tools of our own. When we build software for a client, we check the license terms of the parts we use.

Learn more

• What is free software?The official statement of the four freedoms, for readers who want the exact definition.
• Free Software FoundationThe organization behind the definition, useful for understanding the philosophy.
• Free software on WikipediaA neutral overview of history and licensing for readers new to the topic.