Data compression is the compacting of data by lowering the number of bits which are stored or transmitted. As a result, the compressed data requires less disk space than the initial one, so additional content might be stored on the same amount of space. You'll find different compression algorithms which work in different ways and with some of them just the redundant bits are removed, which means that once the data is uncompressed, there's no decrease in quality. Others erase unneeded bits, but uncompressing the data afterwards will result in lower quality compared to the original. Compressing and uncompressing content needs a large amount of system resources, particularly CPU processing time, so any hosting platform that uses compression in real time should have enough power to support that attribute. An example how information can be compressed is to replace a binary code such as 111111 with 6x1 i.e. "remembering" the number of consecutive 1s or 0s there should be instead of keeping the whole code.