Open Source Software (OSS) is software which source code and other rights, that normally belong exclusively to those who have author rights, are published under a software license compatible with the Open Source Definition or are part of public domain.
Now users are able to use the software for free, change, improve and redistribute the software.
There are several Open Source licenses, such as GNU General Public License (GPL), MIT, Apache License 2.0, Mozilla Public License 2.0 etc.
Here’s how to fix a linux computer
By the Oatmeal, have fun.