K-Lite Codec Pack is a free software on Windows platform, which is used to install various audio and video decoders and related tools. It can help you play almost all popular audio and video file formats on your computer, including but not limited to MP3, AVI, MKV, MP4, FLV, etc. K-Lite Codec Pack usually contains a series of decoders and filters, which enable you to seamlessly play media files of different formats in various media players.