Have a file your dying to play but can't because you don't have the codec?
Need to play a quicktime or realmedia file, but don't want to install the players?
Codec Guide can help with all of these problems. Codec stands for coder/decoder and these are required by audio and video media players, such as Windows Media Player, to play movie and song files. Since media files are created using many formats, numerous formats are also necessary to play these files.
Codec guide has a wide variety of these codecs. They distribute them in 4 packages: the K-Lite Codec Pack Full/Standard/Basic and the K-Lite Mega Codec Pack, which were recently updated. Additionally, they have alternative codecs that can be used to play quicktime files and realmedia files.
from KenR 
