Use these to great effect
An effect file (.fx) contains the whole pipeline state to render something. It is a text file with the variables that are the input, the shaders that work on the input and a number of techniques that use the shaders and also sets the rest of the directx state. Effect files can be used by tools such as Maya and 3DSMax to let artists see the models with the shaders they will use in the game without starting the game.
The shaders are written in HLSL.