HDD - hard disk drive
Hard disk drives (also called hard drives or disk drives) is the mechanism that reads and writes data on a hard disk. Hard disk drives (HDDs) for PCs generally have seek times of about 12 milliseconds or less. Many disk drives improve their performance through a technique called caching.
Hard disk drives are sometimes called Winchester drives, Winchester being the name of one of the first popular hard disk drive technologies developed by IBMin 1973.