Why are there .sln, .suo and .csproj files?

Question

I began to use Visual Studio 2010. After I\'m done with the C# program, I see that there are .sln, and .suo files in the project root directory, an

Answer 1

From MSDN:

A solution (.sln) is a structure for organizing projects in Visual Studio. It performs a function similar to Windows Program Group (.vbg) files in Visual Basic 6.0 and project workspace (.dsw) files in Visual C++ 6.0. The solution maintains the state information for projects in .sln (text-based, shared) and .suo (binary, user-specific solution options) files … [Source]

Furthermore, also from MSDN:

The solution user options (.suo) file is a structured storage, or compound, file stored in a binary format. You save user information into streams with the name of the stream being the key that will be used to identify the information in the .suo file … [Source]

You do not need to put .suo file in VCS. That is a user-specific file.