Whenever you click ‘Save’ in an application, burn files to a CD-R, copy music onto your MP3 player, or drag and drop a file onto memory stick, you are using storage devices - devices that can store and retrieve data.
Serial / Sequential Access
A non-computer serial access device that will be familiar to you is a VHS videotape. Because video is stored on a long piece of tape, when TV shows are recorded onto the tape, they go on one-by-one, in order...
The shows are only accessible in the same order that you recorded them. This type of one-by-one storage and access is called serial access.
Direct / Random Access
An example of a direct access device would be a DVD movie. Unlike the VHS videotape movie, you can jump to any scene on a DVD.
All parts of the DVD are directly accessible. This type of file storage is called direct access.