A settler is a person who has migrated to an area and established permanent residence there, often to colonize the area. Settlers are generally people who take up residence on land and cultivate it, as opposed to nomads. Settlers are sometimes termed "colonists" or "colonials" and -- in the United States -- "pioneers".
The colony concerned is sometimes controlled by the government of a settler's home country, and emigration is sometimes approved by an imperial government. The term settler is not usually used in relation to the later histories of well-established and/or independent, postcolonial countries with continuing immigration, like the present-day United States, Canada or Australia, where terms like immigrants are preferred.
In almost every real historical case, settlers live on land which previously belonged to long-established peoples, known as indigenous people (often called "natives", "Aborigines" or, in the Americas, "Indians"). This land is usually settled against the wishes of the indigenes, and then controlled, defended and expanded by force, or it is bought or leased from indigenous people on terms highly favourable to the settlers, sometimes under a treaty (e.g. the Treaty of Waitangi in New Zealand). In some cases (such as Australia), the legal ownership of some lands is contested much later by indigenous people, who seek or claim traditional usage, land rights, native title and related forms of ownership or partial control.
The word "settler" was not originally usually used in relation to unfree labour immigrants, such as slaves (e.g. in the United States), indentured labourers (such as in Colonial America), or convicts (such as in New York, 1674-1775; Australia 1788-1868).
In the figurative usage a "person who goes first or does something first", also applies to the American English use of "pioneer" to refer to a settler, a person who has migrated to a less occupied area and established permanent residence there, often to colonize the area, first recorded in English in 1605. In United States history it refers to those people who helped to settle new lands.
In this usage, pioneers are usually among the first to an area, whereas settlers can arrive after first settlement and join others in the process of human settlement. This correlates with the work of military pioneers who were tasked with construction of camps before the rest of the troops would arrive at the designated camp site.
More recently descendants of these immigrants may argue that they have as much right to use the word "settler" as the descendants of free immigrants.
In Imperial Russia, the government invited Russians or foreign nationals to settle in sparsely populated lands. These settlers were called "colonists". See, e.g., articles Slavo-Serbia, Volga German, Volhynia, Russians in Kazakhstan.
Although they are often thought of as traveling by sea — the dominant form of travel in the early modern era — significant waves of settlement could also use long overland routes, such as the Great Trek by the Boer-Afrikaners in South Africa, or the Oregon Trail in the United States.