Where i can get open source softwares?

Do you know that where you can find all open source softwares? If you don't know means, this article is for you.

Open source software:
open source means any one can edit and develop the software. Any one can use the source code. It is free for everyone.

Eg:
Wamp server

open source os is linux .

Where you can download it?
You can download all open source softwares in