In the Star Trek fictional universe, the tricorder is a handheld device used for scanning an area, interpreting and displaying data from scans to the user, and recording information to isolinear chips.

Three primary variants of the tricorder are issued by Starfleet: the standard tricorder is a general use device used primarily to scout unfamiliar areas. The medical tricorder is used specifically by doctors to help diagnose diseases and collect bodily information about a patient; the key difference between this and a standard tricorder is a detachable hand-held high-resolution sensor array. The engineering tricorder is a variation on the device fine-tuned for starship engineering purposes. There are also many other lesser-used varieties of special use tricorders.

The tricorder of the 23rd century was a heavy, black, rectangular device with a small screen and a shoulder strap. The 24th century update on the unit is a small, gray, square model with a flip-out panel to allow for a larger screen.

A real-world device comparable to the tricorder was developed by a Canadian company called the Vital Techologies Corporation in 1996. The scanner was called the TR-107 Mark 1; Vital Tech. sold 10,000 of them before going out of business. The TR-107 could scan EM radiation, temperature, and barometric pressure.

Software exists to make hand-held devices simulate a tricorder. Examples include Jeff Jetton's Tricorder - 2.0 for the PalmPilot and the "genuine Tricorder from Elegant Solutions" for the Pocket PC.