The GNU general public license is free and copyright free license for software and many other kinds of work.
Many other licenses on software intend to take away your freedom but a GNU general public license does not do the same. it allows you to share and modify the program so that it remains free for every user.
When we talk of freeware that doesn’t mean that the program is free of cost. Rather, it clarifies that you have the freedom of distributing the copies of that program (and also charge them if you want) and have access to the source code or can get it, and change it the way you want.
While practicing the freedom offered by GNU, one should also take care of others freedom. For instance, if you are distributing the copies of the program you modified under GNU GPL license, the right to modify its source code should also be passed on to the recipient.
The GNU GPL license also clearly explains that there is no warranty for the free software. The program that is modified will be marked as changed and the problem will not be attributed to the authors of the previous versions.
If you have built a program and wanted it to be in the possible use of maximum public, then opting for GNU GPL is the best way. To do so, attach the following notices to the program. The best and the safest way to do it is attach them to the every source file of the program and each file should have copyright and a pointer to where the full notice is found.
<one line to give the program’s name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Also add your contact information in the notice.
For more information about licenses click here.