[j_s]

x64 is one of the 'build platforms' for .NET projects in Visual Studio:

   With Visual Studio 2013 Preview, you can now use [Edit and Continue] with x64, 
   AnyCPU, and (of course) x86 projects.

See also: http://visualstudiohacks.com/articles/visual-studio-net-plat...

[br1]

lostoptimist surely meant running visual studio itself as a 64 bit process to use more than 4 gb of ram