Wave format - *.wav
The Microsoft wave format is a lossless, usually un-compressed audio format. Advantages of the wav format include is cross platform compatibility and ease of editing in various programs. The main disadvantage is a wave files large size.

MP3 format - *.mp3
The MP3 format is the most widely used audio format on the internet. An MP3 file has very good quality in relation to its file size. When creating an MP3 file, you can choose what quality level to save the file as. The MP3 format is cross-platform, and compatible with nearly all media applications.

MPEG – varies, often *.mpg
The MPEG is not a single file format, but rather a “video and audio encoding standard”. There are quite a few different MPEG standards, MPEG-1 and MPEG-4 being the most commonly used for the average consumer.

Windows Media Video - *.wmv
The Windows Media Video format is a common media format for internet usage. It is easily created using Windows Movie Maker (which comes free on any windows computer.) Windows Media Videos can be created using a wide variation of quality settings.

Windows Media Audio - *.wma or *.asf
The Windows Media Audio format is the second most popular media format, second only to Mp3. It is very similar to MP3, except that it supports DRM (Digital rights management).

Quicktime Movie – usually *.mov
The Quicktime Media formats all have a serious disadvantage, in that very few programs support them. You must have Quicktime player to play them, and only a very few programs can edit them. They are far less flexible than many other formats.