Spotters are people who have an almost obsessional interest in something which contains a great deal of variety, but which the majority of people see as mundane, purely functional, and/or identical in form. This interest normally involves some form of collection or logging of detailed data or images, using physical, electronic, or mental means. The group commonly conform to one or more of several stereotypes, such as the wearing of an anorak, or damaged spectacles held together with sellotape or plaster, although these stereotypes do not define the group.

The term seems to have been first applied to people interested in the minutiae of public transport operations, notably railways, although most modes of transport attract such groups of people. It has spread to include other subjects, such as the recognition of musical samples contained in dance and rap music, and the recall of sporting results and associated 'trivia'.

Spotters may be considered geeks or nerds. Both are often social misfits, however spotters may be defined by their obsessional interest in a topic and the collection of associated apparently trivial data, where as geeks and nerds may just be interested in something unusual.

Common terms for spotters include trainspotters, gricers, twitchers (birds), greasers (trains), bashers (trains, mainly travelling), cranks, sellotape, and anoraks. However, the use of the term anorak has recently been adopted to refer to computer geeks, who are not normally spotters.

This category lists sites about spotters as people in society, and their relationship to society. It does not list sites which contain resources useful to spotters, such as databases of vehicles, rolling stock, or records, although it may contain sites primarily aimed at helping people become spotters or supporting generic spotter lifestyles.