Train spotting is a pastime practised in the UK and US (and possibly elsewhere) in which enthusiasts spend time at railway depots, train stations or at trackside vantage points noting down serial numbers of passing trains and locomotives.

The aim of these hobbyists is to see all of the locomotives and perhaps coaching stock and multiple units (coaches with motive power as well as passenger seating) in the country.

The term "train spotter" is often used as a derogatory term towards someone perceived to have an enthusiasm for acquiring or hoarding detailed or humdrum information.

Trainspotting is also the name of a novel and a movie, the reference here being to the "mainlining" of heroin or hanging about in the disbanded Leith railway station.

See also: plane spotters, metrophiles, twitchers, bus spotters, collecting