Often referenced simply as "the GPL." There are multiple versions (GPL-2.0, GPL-3.0, AGPL); they share the copyleft principle but differ on detail.
GPL code is software distributed under the GNU General Public License, one of the original and most widely used open-source licences. Its defining feature is **copyleft**: anyone who distributes a derivative work that contains GPL code must also distribute that derivative under the GPL, with the source code available. The licence is designed to keep code permanently in the open ecosystem rather than allowing it to be absorbed into closed-source products.
For most non-distribution uses — running GPL software internally, learning from it, modifying it for personal use — the copyleft obligation does not trigger. It triggers when the derivative is **shared with people outside your organisation**, which includes most product distributions and many SaaS scenarios (AGPL extends the trigger explicitly to SaaS).
The practical implication for early-career engineers is that incorporating GPL code into a project you might later commercialise or close-source carries a future obligation you should be aware of before starting.
If a challenge submission includes GPL-licensed code, that's fine for the credential — Ewance keeps your submission private. The licensing question matters later, if you decide to commercialise or ship the deliverable as a product. Mixing GPL code into a closed-source product means you'll either need to release the derivative under GPL or replace the GPL portion with permissively-licensed code. Most early-career students will not hit this, but it's worth knowing the obligation exists before you build on top of GPL libraries.
The fastest way to know whether challenge-based learning fits you is to ship one.
