Standard and Nonstandard Language
The written form of a language may have more prestige than the spoken form, and it also may have a more grammar and a vocabulary. A standard written literary language thus tends to influence the speech of educated people. In certain they will try to imitate it when they talk, and they may relegate the unwritten form to situations where prestige is less important. In Arabic-speaking countries, for example, educated people sometimes use Arabic in speech as well as in writing, uneducated people speak only colloquial Arabic. The use of two such varieties of a single language by the same speaker in different situations is called diglossia. People who use the spoken form of a standard literary dialect in public and their native dialect when they are with friends (as do many German-speaking Swiss) are said to be diglossic.

A standard language is that one of the language's dialects that has become . Often, such is due to governmental one dialect is given prestige over others, and various or customs that it is used. The standard language (such as High German) is frequently the dialect used in writing; that is, it is the literary language of a speech , or at least a dialect that has an existing orthography and a body of material written in it.

Few people actually speak such a standard language; rather, they it with their own . The standard dialect is the one that is used when a language is taught to nonnative speakers; the learners then speak it, but do so with an accent, or carried over from their first language and . The standard language also provides a common means of among speakers of dialects (as in the examples given above for German). Standard languages are thus highly useful in efforts to unite people and a sense of national spirit.

Dialect, Argot, and Jargon
A dialect is a variety of a language that differs from other varieties of the same language used in different geographical and by different social groups. For example, Boston who speak the New England dialect of American English drink tonic and frappés, people in Los Angeles sip sodas and milkshakes. Within groups of people who speak the same geographical or social dialect, other language exist that depend on situations. People who have activities in common or share a profession or trade may have a special "language" called an argot that them as from outsiders. Teenagers, thieves, and prostitutes have an argot separating them from parents, police, and other . Such a specialised informal argot is called slang. An argot or specialised terminology, as shared by members of a profession, without any connotation of slang, is called a jargon. groups with jargons include physicians, lawyers, clergy, linguists, and art critics. (The use of the terms argot, jargon, and slang, however, from writer to writer).

Pidgins and Creoles
Just as a language may develop varieties in the form of dialects and argots, languages as a whole may change (Latin, for example, into the different Romance languages). Sometimes rapid language change as a result of between people who each speak a different language. In such a pidgin may arise. Pidgins are grammatically based on one language but are also influenced, especially in vocabulary, by others; they have relatively small sound systems, reduced vocabularies, and simplified and grammars, and they heavily on in order to be understood. Pidgins are often the result of by traders with island and coastal peoples. A pidgin has no native speakers; when speakers of a pidgin have children who learn the pidgin as their first language, that language is then called a creole. Once the creole has enough native speakers to form a speech , the creole may into a fuller language. This is the case with Krio, now the national language of Sierra Leone in West Africa. Krio arose from what was originally an English-based pidgin.