TL;DR* Here's what the license entails:
1. Anyone can copy, modify and distribute this software.
2. You have to include the license and copyright notice with each and every distribution.
3. You can use this software privately.
4. You can use this software for commercial purposes.
5. If you dare build your business solely from this code, you risk open-sourcing the whole code base.
6. If you modify it, you have to indicate changes made to the code.
7. Any modifications of this code base MUST be distributed with the same license, GPLv3.
8. This software is provided without warranty.
9. The software author or license can not be held liable for any damages inflicted by the software.
More information on about the LICENSE can be found here
@vijayaparthiban I don't agree that just by calling another application that application would be bound to GPL3 code unless the code bases intertwine. The goal of the license is to protect intellectual property. Let's say I need a microservice to manage users within my organisation. And I use some opensource solution to implement single signon. I would not need to opensource every single application in the whole organisation just because I use this product (for something it was supposed to be used for). Sure, if you fix something, or you add a nice feature, share it with the community. Don't resell it. As an author that is what you want. The license is not a meant to hyjack your entire organisation. You don't want to put a lot of effort into something, then share it, and witness people claiming your work as their own and make money at the expense of your community. It's fair to set expectations on how the code is distributed. So if I would build another application on top of the opensource product, or include its libraries, and build my business on some cloud based authentication service, then I would obviously violate the license terms. Sure, we live in a world where a laywer can succesfully get money from a company for not warning a dumb customer about putting cats in a microwave, but that's another (legal) story.
Not a single company out there would use, contribute or fund opensource projects that would legally require them to put their entire business on github ^^