The 3.5-inch floppy disk is a type of data storage medium that was widely used from the 1980s to the early 2000s. It is a square, plastic disk encased in a protective shell, measuring 3.5 inches on each side. The disk can store up to 1.44 megabytes of data, making it suitable for saving documents, software, and other files. Floppy disks were commonly used in personal computers and were often used to transfer files between machines. They were eventually replaced by more advanced storage solutions, such as USB flash drives and CDs, due to their limited storage capacity and slower data transfer speeds.