Codec stands for Compressor/Decompressor and is an algorithm for defining compression. Codecs compress your video file into a format for you to use on your computer, portable media player, DVD player, etc. Some codecs come with your computer, others need to be installed.
Depending on which codec you use, you may end up with a proprietary file extension like .flv or .wmv (see glossary to left).
Some codecs bury themselves within a wrapper, or container, like .avi or .mov. A container is a type of file format enclosing various types of data compressed by codecs. These formats are essentially wrappers in that they don't specify what codec is being used, but rather it defines how the video, audio and other data is stored within the container.
If you have a video file and don't know which codec was used, there is software available to help you identify them, such as GSpot (see screenshot below) for Windows, or VideoSpec for a Mac.
|Streaming Media is the sending of a media file over the Internet as a series of small data packets to be viewed in a real time fashion through the use of a Media Player. Unlike downloading (or Podcasting), no files remain on the harddrive once the viewing is complete. Streamed media may originate from a file OR from a live feed camera running through a streaming server. Additionally, streamed media may be assigned multiple bitrates, meaning within the file is encoded the necessary data to stream accordingly to a low bandwidth connection (like dial-up modems) or to a fast connection (like T1).
Often mistaken for streaming, progressive downloading is when a media file on a remote web server is played from the server. This creates a temporary file on your machine. Depending on your connection speed, it can often take extra time for the video playback to catch up to the downloaded information in the temp file, which is called buffering.