The Zip system was based loosely on Iomega's earlier Bernoulli Box system; in both systems, a set of read/write heads mounted on a linear actuator flies over a rapidly spinning floppy disk mounted in a sturdy cartridge. The Zip disk used smaller media (about the size of a 3.5" microfloppy, rather than the compact disc-sized Bernoulli media), and a simplified drive design that reduced its cost. This gave a drive that held much more than a regular floppy, with data transfer rates and seek times (about 1 megabyte/second and 28 milliseconds on average) that (while not directly competitive with hard drives) were much quicker than a standard floppy drive.
The Zip system was introduced with a capacity of 100 megabytes, and quickly became a success as people used them to hold large files (especially bitmaps) that regular floppy disks would not be able to handle. As time went on, Iomega eventually increased the capacity to 250 and later 750 megabytes, while improving the data transfer rate and seek times.
The Zip's popularity started to fade around 2000. By this time, several people had reliability problems with their Zip drives (especially the click of death), and the relatively high cost per megabyte of the proprietary cartridges was becoming unattractive, compared to the falling costs of CD-R and DVD+-RW technology.