What is MathLink?

MathLink is Wolfram Research's protocol for sending data and commands back and forth between Mathematica and other programs. MathLink is the underlying glue that lets .NET and Mathematica talk to each other. When calling .NET from Mathematica, .NET/Link completely hides the low-level details of the MathLink communication, allowing Mathematica programmers to load and use .NET classes as if they were part of the Mathematica environment itself. When writing .NET programs that call Mathematica, .NET/Link provides a higher-level layer of functionality than the traditional C MathLink programming interface.