PKzip

PKzip is one of the most recognizable compression utilities from the DOS era and became almost unavoidable in the world of downloadable software. Its main job is simple: compress files to save disk space and package collections of files into a single archive. That sounds mundane now, but in the days of floppy disks, tiny hard drives, and painfully slow connections, compression could make the difference between convenient and impossible. PKZIP's command-line interface is wonderfully straightforward once you learn the syntax, although newcomers may initially wonder why the computer seems determined to make a simple operation sound like a military order. Its ZIP format eventually became ubiquitous, turning a humble DOS utility into one of the most influential pieces of everyday computing software. Even people who have never heard of PKZIP have probably encountered the format it helped popularize. Few utilities can claim to have made 'zip the files' a universal computer habit.