In computer terms, unzip refers to the act of decompressing a file that was compressed to the
zip file format. Compressed files can be created by using a file compression program or utility like, winzip, pkzip, 7-zip and numerous others . File compression is used to reduce a file’s size and is ideal for reducing the size of file attachments in emails . The “zip” format is just one of many file compression formats and is supported by most compression programs and some of the latest operating systems.