Source control in Visual Studio 2010?

After doing some search on SO, Google and MSDN forums I've become frustrated that there is so little information for what might seem like an obvious question and possibly a dumb question.

I need to use source control in Visual Studio 2010 Professional. I do not have separate Team Foundation Server 2010. Some people have mentioned SourceSafe? I haven't seen any SourceSafe inside of the Visual Studio 2010 to be honest.

What are some alternatives (preferably free) for source control in Visual Studio 2010? Or is it already integrated in Visual Studio 2010 that I am so blind to have missed that?

Update #1: Thank you everyone, I will go with SVN, in particular AnkhSVN for Visual Studio 2010.

Update 3/23/2011: It's been almost a year since I have asked this question. I highly recommend using either Mercurial or Git over Subversion. So for those of you who are looking for Visual Studio 2010 version control system, look no further than Git or Mercurial extensions from the Visual Studio Extension Library.

Update 5/16/2013: I would now strongly encourage you to use Git over Mercurial, TFS or SVN. Take a look at CodeSchool's Try GitHub in the browser to see how awesome it is!

• Getting Started with Git on Visual Studio 2012 - in-depth tutorial by Andy Lewis.

• Visual Studio Tools for Git - An extension for Team Explorer to provide source control integration for Git. Enables integration with local Git repositories and provides tools to work with remote repositories.

See: List of Source Control Systems with Visual Studio Plugins

Visual Studio is just an IDE. You can use any source control solution that you want with it. Any open source source control solution in particular, like git, mercurial (hg) or subversion (svn). And there are commercial products like Perforce or SourceGear Vault. See here for a pretty exhaustive list and google for more information.

You can find Visual Studio plugins that integrate it with any source control. Of open source ones subversion is especially rich in this regard. Commercial ones usually come with this integration.

And if you are not using source control that requires you to explicitly check-out files to edit them (like VSS or TFS do), the IDE integration is not even essential. I personally prefer to use git or subversion from outside the IDE.

And please, stay as far from Visual SourceSafe as you can.