You usually realize you need this package when you see errors like: "The program can't start because MSVCR90.dll is missing." "Runtime Error!"

This is the most common symptom of a missing or corrupted Visual C++ 2008 SP1 (x64) redistributable. The error messages vary, but they typically look like:

Everything You Need to Know About Microsoft Visual C++ 2008 SP1 Redistributable (x64)