Comment by moron4hire

That is completely incorrect. The GPL makes absolutely zero restriction on use. It's provisions only pertain to distribution.

If you are only using GPL'd software, there is no compulsion to release your software under the GPL. If you, on the other hand, are releasing a product to other people and you have found a piece of GPL'd software that provides enough value to you to bother including it in your project, then and only then are you compelled to open your source.