Glossary
Hashing (hash)
Turning a piece of data into a unique, non-reversible "fingerprint", useful for checking a file or protecting a password.
Hashing computes a fixed-size fingerprint from a piece of data; you cannot go back to the original data from the fingerprint. It is used to check that a file has not been altered (the slightest change alters the fingerprint) and to store passwords without keeping them in the clear. Unlike encryption, it is not reversible.
See also
Trojan horse (trojan)A booby-trapped program that hides inside normal-looking software and activates once you install it.Computer worm (worm)Malicious software that spreads on its own from one machine to another, without anyone having to click.SpywareSoftware that quietly watches your device to collect information without your knowledge.RootkitMalicious software that takes deep control of a machine while making itself invisible.