File compression—sometimes referred to as data compression—is a way to reduce overall file size to make large files more manageable. It can make large files easier to share or download, and take up less space on your hard drive. Compressed file types are ZIP and RAR most commonly, but can also be ARC, ARJ, or CAB.
File compression works by encoding information into fewer bits than the original by removing redundant data in the file. Most file compression methods are lossless, which means that you won’t lose any data or quality during the compression. Both Mac and Windows devices have file compression features built in to their OS, so you can easily compress your files into zipped folders on your desktop.