What is the different between MPEG, MPEG2, AVI and WMV

There is a confusing alphabet soup of acronyms for video. In the list above, you actually have three different types of entities: standards organizations (MPEG), encodings (MPEG2, WMV) and containers (AVI, WMV). From the standards committees, comes specs to implement conforming encoders/decoders for multiple variations of the standards. For example, MPEG2 or MPEG4, which can be implemented with various profiles and levels. Levels are used to support variations such as standard definition vs. high-definition. Container types serve to make it even more confusing. Think of a container type as the file extension/file format for all those audio and video files. Many types of containers support multiple types of encodings inside. For example, the popular .avi file format can contain different types of video encodings. Also, keep in mind that .mpg files can also contain different audio endodings (e.g. Dolby Digital vs. PCM vs. MPEG1-Layer2) Lastly, some people just have to be different, like Microsoft. The WMV format can be thought of as both a container and an encoding. It's a container, because it's a file format for packaging video data. It's an encoding, because Microsoft implemented a non-standard variant of MPEG4. Now, back to practical issues. First, decide if you want your video to make DVD's or to use on your PC. If it's DVD's, the answer is simple, because DVD's are MPEG2 currently. Use MPEG2, unless you want to hassle re-encoding. If it's to use on a computer or some other special application, then you have more options. The two big variables are quality and size. Newer encoding formats such as MPEG4 and WMV achieve significantly better compression, without sacrificing quality. You may find better tools available for MPEG2 though, since it is the reigning king. Look for the newer encodings to blow it away in the future, especially as the move to high-definition video takes hold.