There are a lot of open source projects where one can borrow the works of others for free. However, many come with caveats. If you are using open source projects within yours, you should check for their licenses.
The intention of these licenses is to encourage the development and adoption of open source projects. That is, to foster innovation and collaboration, and to improve availability (as the saying goes, “Don’t reinvent the wheel”)
If you use your work only for yourself, you don’t have to worry about these licenses.
However, when you make your software available to others, either free or paid, then these licenses require you to follow certain rules.
The code you borrow from others will fall under one of the three categories:
- Public domain
- Permissive licenses (aka academic licenses)
- e.g. MIT, BSD, and Apache licenses
- Copyleft licenses
- e.g. GPL, AGPL, and LGPL licenses
- Copyleft is a word play on the word “copyright”. Copyright ensures your right to your work, whereas copyleft ensures your work remain free for everyone.
Public domain means anyone can use the work without permissions or limitations.
Permissive licenses mainly
- require attribution (giving credits to the original authors)
- and assume no liability (providing no warranties and no guarantees)
but some may require more
Copyleft licenses impose stricter rules and are intended to keep the derivative works also open source.
Copy licenses mainly require
- copyleft (derivative works remain open source)
- reciprocity (derivative works are shared under the same licenses)
- perpetuity (no additional restrictions can be added)
but some may require more
Lastly, open source licenses are applied to all distributed softwares, but are generally not applied to software available over network (e.g. web) unless explicitly stated.
In the next post, I will discuss what licenses are widely adopted and how each license is different.