K-Lite Codec Pack is a collection of codecs and DirectShow filters. Those components are needed for encoding and decoding various audio and video formats. This Codec Pack is designed as a user-friendly solution for playing all your movie files.

Full supports both playback and encoding. This package is for power users and people who do their own encodings.
Standard contains everything you need to play all the commonly used formats. This package should be enough for the average user.