Diglossia literally means “two tongues.” This definition gives the impression that diglossia and bilingualism are the same thing. However, diglossia is a distinct form of bilingualism in that the use of the two languages are determined by the function.

A diglossia consists of a high and low language. The high language is used for specific purposes such as business transactions, ceremonies, and religious rites. The low language is used for everyday conversation. You would never hear a person use the low language for normal conversation.

The context in which the high and low languages are used are called domains. There are many different domains such as family, work, school, church, etc. Each of these domains calls for either the high or low language. For example, the high language may be used when speaking of politics while the low language may be used for speaking about sports.

There are several examples of diglossia in the world. In America, African Americans often have their own distinct form of English which functions as a low language. Regular or standard English would be the high language in this situation. At home, African American English is spoken and in public, a switch to standard English is often made.

There is often an interaction between diglossia and bilingualism in language. In general, there are four ways in which diglossia and bilingualism can interact in a community.

1. The community has diglossia and bilingualism
2. The community has diglossia but not bilingualism
3. The community has bilingualism but diglossia
4. The community does not have diglossia or bilingualism

Below are examples of each

Diglossia and Bilingualism 

An example of this is an African American community where the people can speak standard English (high language), African American English (low language) while also being fluent in another language like Spanish (second language).

Diglossia but not Bilingualism

Same as above, the African American community knows standard English as well as African American English but the community does not speak Spanish or any other language.

Bilingualism but no Diglossia

The African American community speaks standard English and also speaks another language, such as Spanish, but does not use African American English.

Neither Diglossia or Bilingualism

The African American community only speaks standard English and does not speak African American English or any other language such as Spanish.

Conclusion

Communities vary in their perception of their high and low languages. Some look down on the low language while using it while others are proud of the low language while feeling forced to learn the high. The points are that with diglossia, the use of a second language is connected to a particular social setting.