You use OSS projects everyday. VS Code, TensorFlow, React-Native, most NPM packages etc.
And as it is in the name, is changeable (within reason obviously) by anyone. Report bugs, solve bugs, new features, suggest new features...
All for the common good of improving software.
I personally don't have as much time as I use to therefore do not contribute anymore, but I use to!
So do you contribute to OSS and if so/not why?