Colonization (or colonisation) occurs whenever any one or more species populate an area. The term, which is derived from the Latin colere, "to inhabit, cultivate, frequent, practice, tend, guard, respect", originally related to humans. However, 19th century biogeographers dominated the term to describe the activities of birds, bacteria, or plant species. (In the 1990s it became synonymous with the X-Files as a reference to alien colonization). Human colonization is a narrower category than the related concept of colonialism, because whereas colonization refers to settler colonies, trading posts, and plantations, colonialism deals with this and the ruling of new territories' existing peoples.