Data loss, sometimes called a data loss event, is an information technology term that refers to computer data being permanently lost due to unexpected circumstances. Some common causes of losing data are power failure, intentional or unintentional deletion of computer files or programs, various hardware and software problems, a malicious computer virus, or computer hacking. There are various types of data loss, for example data truncation, which makes data unavailable to users because it is not properly stored; corrupted data, which inserts errors into the data making it inaccessible or ineffective; and complete loss of data, which can happen if files are deleted. In many cases, data recovery can be performed to regain access to lost data, but this is not always possible. To avoid losing data, it is recommended that users do regular and frequent backups of data, using multiple hard disk partitions, and also install power-surge protectors and battery backup systems.
There are ways other than data loss that a user can lose access to data. For example, data unavailability occurs when data is inaccessible because of power outages, network problems or other temporary issues. Unlike data loss, this loss of access to data is not permanent. Data can also be stolen or otherwise obtained by an unauthorized party, sometimes called a data spill or data leak. However, a data spill does not always result in data being lost from the original computer.
Recovery of data is sometimes possible using specific procedures. For example, hard drive recovery can be done by qualified computer technicians, and corrupted partitions can often be restored. In some cases, accidentally deleted files can be re-assembled and data restored. One of the easiest ways to avoid problems related to data loss is to make a backup copy of one's computer files and programs that can be used to restore lost data. This backup should be stored on a safe medium such as a separate hard drive or computer, CDs, or memory sticks.
In some cases of data loss, the data is unrecoverable. For example, if files are overwritten rather than simply deleted, the data is usually permanently lost. Therefore, it is not recommended to add new data to a computer if data has been lost until data recovery has been attempted. Also, physical damage to the hard disk can often make data impossible to recover. Rebooting a computer repeatedly if it has suffered data loss due to physical hard disk problems can make the problems worse.