Codecs? File types? Oh my! If you have ever tried to watch a video you downloaded from the internet only to find it unable to be played (or maybe just audio but no video), then this is the guide for you! We're going to try to do our best to cover most of the more common file types that are out there, and what they mean to you and your home theater experience. Before we get into the details, let's cover the basics of the terminology. Codec is an acronym for compressingdecompressing. This technology is used to execute an algorithm to compress or decompress video or audio. An example of this is playback of your PVR recordings on your HTPC; when the file plays back your PC is decompressing, or decoding, the MPEG-2 or H.264 video and MPEG-Audio or AC-3 audio contained in the file.