A dialect (from the Greek word διάλεκτος, dialektos) is a variety of a language used by people from a particular geographic area. The number of speakers, and the area itself, can be of size. It follows that a dialect for a larger area can contain plenty of (sub-) dialects, which in turn can contain dialects of yet smaller areas, et cetera.

The vernacular is the native language of a country or locality.

In previous centuries scholarly work in western Europe was typically written in Latin, so the works written in a native language (such as Italian or German) were said to be in the vernacular.

The vernacular is also often contrasted with a liturgical language. For example, until the 1960s, Latin Rite Roman Catholics held masses in Latin rather than in local vernacular language, to this day the Coptic Church holds liturgies in Coptic, the Ethiopian Orthodox Church holds liturgies in Ge'ez, etc. The Reformation was spread by the publication of Bibles and other religious writings in the vernacular, and the reforms of the Second Vatican Council permitted the use of vernacular liturgies in Roman Catholicism.