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

The SUO files do have a purpose and I disagree with the statement that they should always be ignored. I do not ignore them, and as a general practice I add them to our SVN repository. My projects are not always using the solution defaults for Startup Project or platform. I find it annoying that if I grab a new project it does not default to 64 bit and the proper platform. The SUO contains the settings to set these defaults properly.

The down side of this is that it's a binary file, so pretty much each time you open the solution and do anything the file will have changed. Typically the file is less than 100k, and unless you know you changed something, I don't commit the change.