A maid, housemaid, or maidservant is a female domestic worker. In the Victorian era, domestic service was the second-largest category of employment in England and Wales, after agricultural work. In developed Western nations, full-time maids are now typically only found in the wealthiest households. In other parts of the world, maids remain common in urban middle-class households.

A domestic worker is a person who works within a residence and performs a variety of household services for an individual, from providing cleaning and household maintenance, or cooking, laundry and ironing, or care for children and elderly dependents, and other household errands. The term "'domestic service" applies to the equivalent occupational category. In traditional English contexts, such a person was said to be "in service".