A file is a separate chunk of data designated to be/do one thing. A file can be an program, an image, a video. A data is always the same piece of code, the file extension (.txt, .png...) lets the computer know which program opens it.


Compression is encoding data in a different way using an algorithm to make it take less memory while keeping all the original information. The reverse process is decompression. The ratio of the compressed data size to the original data sazed is a compression ratio (lower is better). It is used in data/files with a lot of redundancy such as video, but can also be done for things like RAM. Compression can be lossless or lossy (drops information of of low importance). A definition list in an encyclopedia is an example of non-computer compression.

File Types