A disk drive is a device that reads and/or writes data to a disk. The most common type of disk drive is a hard drive (or "hard disk drive"), but several other types of disk drives exist as well. Some examples include removable storage devices, floppy drives, and optical drives, which read optical media, such as CDs and DVDs.
While there are multiple types of disk drives, they all work in a similar fashion. Each drive operates by spinning a disk and reading data from it using a small component called a drive head. Hard drives and removable disk drives use a magnetic head, while optical drives use a laser. CD and DVD burners include a high-powered laser that can imprint data onto discs.
Since hard drives are now available in such large capacities, there is little need for removable disk drives. Instead of expanding a system's storage capacity with removable media, most people now use external hard drives instead. While CD and DVD drives are still common, they have become less used since software, movies, and music can now often be downloaded from the Internet. Therefore, internal hard drives and external hard drives are the most common types of disk drives used today.