A thing, also known as a folkmoot, assembly, tribal council, and by other names, was a governing assembly in early Germanic society, made up of the free people of the community presided over by a lawspeaker. Things took place regularly, usually at prominent places accessible by travel. They provided legislative functions, as well as social events and trade opportunities. In modern usage, the meaning of this word in English and other languages has shifted to mean not just an assemblage of some sort but also simply an object of any kind. Thingstead (Old English: þingstede) or thingstow (Old English: þingstōw) is the English term for the location where a thing was held.

The word appears in Old Norse, Old English, and modern Icelandic as þing, in Middle English (as in modern English), Old Saxon, Old Dutch, and Old Frisian as thing (the difference between þing and thing is purely orthographical), in German as Ding, in Dutch and Afrikaans as ding, and in modern Norwegian, Danish, Swedish, Faroese, Gutnish, and Norn as ting. The place where a thing was held was called a thingstead or thingstow. An alternative Proto-Germanic form of the word thing was *þingsō, whence Gothic þeihs time. All of these terms derive from *þingą meaning "appointed time," possibly originating in Proto-Indo-European *ten-, "stretch," as in a "stretch of time for an assembly".

In English, the term is attested from 685 to 686 in the older meaning "assembly"; later, it referred to a being, entity or matter (sometime before 899), and then also an act, deed, or event (from about 1000). The original sense of "meeting, assembly" did not survive the shift to Middle English. The meaning of personal possessions, commonly in the plural, first appears in Middle English around 1300, and eventually led to the modern sense of "object". This semantic development from "assembly" to "object" is mirrored in the evolution of the Latin causa ("judicial lawsuit", "case") to modern French chose, Spanish/Italian/Catalan cosa, and Portuguese coisa (all meaning "object" or "thing") and the cognate to English sake (purpose), sak in Norwegian and Swedish, sag in Danish, zaak in Dutch, saak in Afrikaans, and Sache in German, which in languages like Old Norse meant "accusation, lawsuit," but today also carries the sense "thing, object".

Today the term lives on in the English term hustings and in the names of national legislatures and political and judicial institutions of some Nordic countries (e.g. the Icelandic parliament, the Alþing and the Norwegian parliament, the Storting) and the Isle of Man (the Tynwald).

The first detailed description of a thing was made by Tacitus in 98 CE. Tacitus suggested that the things were annual delegate-based meetings that served legal and military functions.

The oldest written reference to a thing is on a stone pillar found along Hadrian's Wall at Housesteads Roman Fort in Northumberland in the United Kingdom. It is dated 43–410 CE and reads:

DEO MARTI THINCSO ET DUABUS ALAISIAGIS BEDE ET FIMMILENE ET N AUG GERM CIVES TUIHANTI VSLM

To the god Mars Thincsus and the two Alaisiagae, Beda and Fimmilena, and to the Divinity of the Emperor the Germanics, being tribesmen of Tuihanti, willingly and deservedly fulfilled their vow.