Data compression is the compacting of info by decreasing the number of bits which are stored or transmitted. This way, the compressed information will take considerably less disk space than the original one, so more content could be stored on identical amount of space. You'll find various compression algorithms that work in different ways and with a number of them only the redundant bits are deleted, so once the info is uncompressed, there is no decrease in quality. Others delete unnecessary bits, but uncompressing the data at a later time will result in lower quality in comparison with the original. Compressing and uncompressing content consumes a large amount of system resources, and in particular CPU processing time, so every web hosting platform that uses compression in real time needs to have sufficient power to support that feature. An example how information can be compressed is to substitute a binary code such as 111111 with 6x1 i.e. "remembering" how many consecutive 1s or 0s there should be instead of saving the entire code.