The concept of the au pair originated in Europe after World War II. Before the war, an abundant supply of domestic servants had been available to look after the children of middle and upper-class families, but changes in social attitudes, and increases in wages and taxes after the war, made the old system inaccessible to most middle-class parents. At the same time, social change increased the number of middle-class girls who needed to earn their own living, and rising educational aspirations for girls made experiencing foreign cultures and learning foreign languages more common aspirations.

However, due to the stigma attached to being a “servant”, an essentially working-class status that even working-class people were repudiating, this potential supply for domestic labour could only be utilised if a new non-servant role was created. Thus the au pair was born. The au pair was supposed to be treated as a member of the family rather than a servant, and was not required to wear a uniform.

An au pair receives an allowance and their own room. The usual practice is that au pairs eat with the family most of the time, and join in some of the usual family activities such as outings and trips. However, host families ordinarily expect to have some private time to themselves, particularly in the evenings. During this time, an au pair might retire to their room to watch television, study, or go out with friends. Provision is often made for the au pair to have time for studying, especially the language of the host country. The Council of Europe recommends that au pairs be issued standard contracts with their family.

Some au pairs are now male, but females remain the overwhelming majority. Many governments impose limits as to how many hours an au pair is allowed to work. Tasks can include taking children to and from school, taking children to after-school activities, cooking, cleaning, ironing, tidying up and babysitting. Each placement varies depending on the host family.

In many developing countries, an abundant supply of local domestic labour is still available, so there is little or no demand for au pairs.

Au pair relationships between host families and au pairs can be established through various means. Traditionally, au pair agencies located in a given host country have served as an intermediary between young people seeking to become au pairs and families in the country that are interested in hosting an au pair. Such agencies typically charge a fee to the host family for fulfilling an intermediary role between the host family and possible au pairs. The agency conducts some process of screening and evaluation of prospective au pairs and then proposes possible au pairs to the host families, who are their principal customers. Traditional agencies also assist with the arrangement of some of the bureaucratic formalities associated with an au pair visit.

In recent years, the basic function of bringing aspiring au pairs and interested host families together has increasingly been provided by websites that allow families and au pairs to post online profiles and search for each other directly on the basis of the information provided in these profiles. Such websites supplement this search functionality with various information offerings about au pair requirements in different countries as well as by providing user support for their registered users. Charges are made to users of such websites to allow a full exchange of the personal contact details necessary for finalizing an au pair placement.

This approach typically gives prospective au pairs and host families a wider range of choices and more direct control over the selection process than is possible through a traditional agency at a considerably lower price than traditional agencies charge. At the same time, use of such websites requires an aspiring host family or au pair to invest more personal effort in the search process and to make their selection and arrange the formalities of an au pair stay without the involve ment of a third party.