SM or sm may refer to:
Smallpox was an infectious disease caused by one of two virus variants, variola major and variola minor.
Smallville is an American television series developed by writer-producers Alfred Gough and Miles Millar, based on the DC Comics character Superman created by Jerry Siegel and Joe Shuster.
Smosh is an American sketch comedy YouTube channel created by Ian Hecox (born November 30, 1987) and Anthony Padilla (; born September 16, 1987).
SMS (short message service) is a text messaging service component of most telephone, internet, and mobile-device systems.
A smart card, chip card, or integrated circuit card (ICC), is a physical electronic authorization device, used to control access to a resource.