Disk made up of a circular thin plastic jacket coated with magnetic material is called Floppy Disk.

Floppy Disk:
- A floppy disk is a magnetic storage medium that is composed of a thin and flexible disk of a plastic material.
- The disk jacket is circular in shape and coated with a magnetic material that stores data.
- The floppy disk is considered an outdated storage device due to its limited storage capacity and slow reading and writing speed.
- The floppy disk was popular in the 1980s and 1990s for storing small amounts of data, such as text documents and images.
- Floppy disks come in different sizes, with the most common being the 3.5-inch floppy disk that can store up to 1.44 megabytes of data.

Other Types of Disks:
- Hard Disk: A hard disk is a non-removable magnetic disk that stores data on a computer. It is made up of a stack of rigid platters coated with magnetic material.
- Compact Disk (CD): A CD is an optical storage medium that stores data using laser technology. It consists of a plastic disk with a reflective layer and a protective coating.
- DVD: A DVD is an optical storage medium that is similar to a CD but can store more data. It is used to store movies, music, and software.

Conclusion:
In summary, a floppy disk is a circular thin plastic jacket coated with magnetic material that stores data. It is an outdated storage device that was popular in the 1980s and 1990s. Other types of disks include hard disks, CDs, and DVDs.