Prestige in sociolinguistics is the level of regard normally accorded a specific language or dialect within a speech community, relative to other languages or dialects. Prestige varieties are language or dialect families which are generally considered by a society to be the most "correct" or otherwise superior. In many cases, they are the standard form of the language, though there are exceptions, particularly in situations of covert prestige (where a non-standard dialect is highly valued). In addition to dialects and languages, prestige is also applied to smaller linguistic features, such as the pronunciation or usage of words or grammatical constructs, which may not be distinctive enough to constitute a separate dialect. The concept of prestige provides one explanation for the phenomenon of variation in form among speakers of a language or languages.

The presence of prestige dialects is a result of the relationship between the prestige of a group of people and the language that they use. Generally, the language or variety that is regarded as more prestigious in that community is the one used by the more prestigious group. The level of prestige a group has can also influence whether the language that they speak is considered its own language or a dialect (implying that it does not have enough prestige to be considered its own language).

Social class has a correlation with the language that is considered more prestigious, and studies in different communities have shown that sometimes members of a lower social class attempt to emulate the language of individuals in higher social classes to avoid how their distinct language would otherwise construct their identity. The relationship between language and identity construction as a result of prestige influences the language used by different individuals, depending on to which groups they belong or want to belong.

Sociolinguistic prestige is especially visible in situations where two or more distinct languages are used, and in diverse, socially stratified urban areas, in which there are likely to be speakers of different languages and/or dialects interacting often. The result of language contact depends on the power relationship between the languages of the groups that are in contact.

The prevailing view among contemporary linguists is that, regardless of perceptions that a dialect or language is "better" or "worse" than its counterparts, when dialects and languages are assessed "on purely linguistic grounds, all languages—and all dialects—have equal merit".

Additionally, which varieties, registers or features will be considered more prestigious depends on audience and context. There are thus the concepts of overt and covert prestige. Overt prestige is related to standard and "formal" language features, and expresses power and status; covert prestige is related more to vernacular and often patois, and expresses solidarity, community and group identity more than authority.

Prestige varieties are those that are regarded mostly highly within a society. As such, the standard language, the form promoted by authorities—usually governmental or from those in power—and considered "correct" or otherwise superior, is often the prestige variety. However, there are many exceptions to this rule, such as Arabic, in which Egyptian Arabic is widely used in mass media aimed at international audiences, while Literary Arabic (also known as Standard Arabic) is a more prestigious form. Prestige varieties do not exhibit features, grammatically speaking, which prove them superior in terms of logic, efficacy or aesthetics. With certain exceptions, they are the language varieties of the prestigious social classes. Therefore, the prestige variety of a given language community or nation-state has symbolic significance and may act as an instrument of political power.

The notion of a standard language in a speech community is related to the prestige of the languages spoken in the community. In general, "greater prestige tends to be attached to the notion of the standard, since it can function in higher domains, and has a written form." While there are some counterexamples, such as Arabic, "prestigious and standard varieties [tend to] coincide to the extent that the two terms can be used interchangeably."