Final answer:
A head crash is when the read-write head of a hard disk drive damages the magnetic surface of the disk platters, commonly leading to data loss and requiring professional recovery services.
Step-by-step explanation:
When the head damages the magnetic surface, it is known as a head crash. This is a type of failure that can occur in a hard disk drive when the read-write head comes into contact with the coating of the disk platters, which is where data is stored. This can be caused by shock, wear and tear, or manufacturing defects, and often results in data loss.
A head crash can be a serious problem because it not only damages the physical hard drive but can also lead to the corruption or loss of the data stored on the disk. It is important to back up data regularly to avoid the consequences of such a failure. If a head crash occurs, professional data recovery services may be necessary to salvage the information on the drive.