Open Source License Selector

Yes. Without one, your code is legally "all rights reserved" by default — nobody can legally use, copy, or distribute it, even if it's publicly visible on GitHub.

You can relicense future versions, but you cannot retroactively change the license for code already distributed. For projects with multiple contributors, you'd need agreement from every copyright holder — which is rarely practical. Choose carefully upfront.

License obligations generally apply when you distribute software. If you run it internally and never distribute it, most licenses impose no requirements — even copyleft ones. AGPL is the exception: it also covers network use.

Yes. MIT is compatible with GPL — you can include MIT code in a GPL project. The combined work must be distributed under GPL. The reverse isn't true: you cannot include GPL code in an MIT-licensed project, because GPL is more restrictive.

Each contributor holds copyright over their own contributions. The project license governs how the whole can be used, but changing it later requires agreement from all contributors. Some projects use a Contributor License Agreement (CLA) to manage this upfront.