A file compressor is a program that is able to reduce the amount of memory a file takes up. Unlike other compressors, this one temporarily turns the compressed file into a different file format. Most files have repeating characters and coding, and a file compressor identifies the redundant information and compresses it. If the file has a high amount of redundancy, then the compression will be greater. The general use of this compressor is to make it easier to store, download and transmit a compressed file, but the file also can be used to archive important system information.
When most compressors are used on a file, they do two things: They minimize the memory of the file, and they permanently change the file’s format. With a file compressor, the compressed file is typically changed into another format, but the file’s original format returns once the compressed file is opened. The format typically is changed to help facilitate compression rates. There are many different compression formats for general file compressor programs, and each one serves a different purpose.
Most files have repeating information. To reduce the memory of these files, a file compressor removes all instances — except the first instance — of the repeating data and saves them in a low-memory archive file. For example, many files and programs have programming tags, and the compressor will remove all but the first instance of these tags. When compressed files are returned to normal size, the archive file returns the redundant information to the files and they will act like they did before compression.
Judging how much memory a file compressor can save is usually difficult, because it depends on the amount of redundancy and the compression output. On average, compression reduces from 5 percent to 30 percent of a file’s size. Compression formats made for long-term archiving often reduce more memory than short-term formats. This means a 1 gigabyte (GB) file normally will be around 995 megabytes (MB) to 700 MB after compression.
A file compressor normally is used to make general files smaller and easier to store or download. The files are smaller, so they take up less hard drive space, require fewer resources to download, and take less time to transfer between computers and networks. Backup and archival files, both of which are meant for long-term storage and often contain system data, are easier to store and usually will not make a noticeable dent in the hard drive space.