Toponymy, toponymics, or toponomastics is the study of toponyms (proper names of places, also known as place names and geographic names), including their origins, meanings, usage, and types. Toponym is the general term for a proper name of any geographical feature, and full scope of the term also includes proper names of all cosmographical features.

In a more specific sense, the term toponymy refers to an inventory of toponyms, while the discipline researching such names is referred to as toponymics or toponomastics. Toponymy is a branch of onomastics, the study of proper names of all kinds. A person who studies toponymy is called toponymist.

The term toponymy comes from Ancient Greek: τόπος / tópos, 'place', and ὄνομα / onoma, 'name'. The Oxford English Dictionary records toponymy (meaning "place name") first appearing in English in 1876 in the context of geographical studies. Since then, toponym has come to replace the term place-name in professional discourse among geographers.

Toponyms can be divided in two principal groups:

Various types of geographical toponyms (geonyms) include, in alphabetical order:

Various types of cosmographical toponyms (cosmonyms) include:

A simplex toponym consists of just one morpheme that identifies the geographic feature by itself, whereas a composite toponym can be broken down into multiple elements, namely, a specific that distinguishes the feature from others within its class and a generic that distinguishes the feature from others with the same name in other classes. In English, a composite toponym may consist of a specific and a generic (such as "Tweed River", "River Tweed", or "River Road") or less commonly a generic with a definite article (such as "The Bend" or "The Dalles").

Probably the first toponymists were the storytellers and poets who explained the origin of specific place names as part of their tales; sometimes place-names served as the basis for their etiological legends. The process of folk etymology usually took over, whereby a false meaning was extracted from a name based on its structure or sounds. Thus, for example, the toponym of Hellespont was explained by Greek poets as being named after Helle, daughter of Athamas, who drowned there as she crossed it with her brother Phrixus on a flying golden ram. The name, however, is probably derived from an older language, such as Pelasgian, which was unknown to those who explained its origin. In his Names on the Globe, George R. Stewart theorizes that Hellespont originally meant something like 'narrow Pontus' or 'entrance to Pontus', Pontus being an ancient name for the region around the Black Sea, and by extension, for the sea itself.