Can I use C# to develop with Unity?

Sorry that this is common question or maybe silly question because I am totally new to game develop.

I heard Game developer using C++ for performance reason.

I want to learn Unity for windows store app games. and I am specialized in C#.

Can I use my C# skills in developing with Unity for game?

Please forgive me this silly question.

I tried to find these question in the forum but can' find it :)