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 (mainly within the continent of Asia), maids remain common in urban middle-class households.

Maid in Middle English meant an unmarried woman, especially a young one, or specifically a virgin. These meanings lived on in English until recent times (and are still familiar from literature and folk music), alongside the sense of the word as a type of servant.

Maids perform typical domestic chores such as laundry, ironing, cleaning the house, grocery shopping, cooking, and caring for household pets. They may also take care of children, although there are more specific occupations for this, such as nanny. In some poor countries, maids take care of the elderly and people with disabilities. Many maids are required by their employers to wear a uniform.

In the contemporary Western world, comparatively few households can afford live-in domestic help, usually relying on cleaners, employed directly or through an agency (maid service). Many services historically provided by maids have been substituted with home appliances.

In less developed nations, various factors ensure a labour source for domestic work: very large differences in the income of urban and rural households, widespread poverty, fewer educated women, and limited opportunities for the employment of less educated women.

Legislation in many countries makes certain living conditions, working hours, or minimum wage a requirement of domestic service. Nonetheless, the work of a maid has always been hard, involving a full day, and extensive duties. Maids would be familiar with hard work and typically worked long hours in a week.

Maids were once part of an elaborate hierarchy in great houses, where the retinue of servants stretched up to the housekeeper and butler, responsible for female and male employees respectively. It was the most common way that women could earn money, especially lower class women. Domestic workers, particularly those low in the hierarchy, such as maids and footmen, were expected to remain unmarried while in service. They sometimes had their own section of rooms in the house, though they were often far away from the other rooms and more simply furnished than the rest of the house.

In Victorian England, all middle-class families would have employed staff, but for most small households, this would be only one employee, the maid of all work. Some households employed maids-of-all-work as young as twelve in 19th-century England. They often worked from five in the morning until late in the evening on a wage of £6 to £9 per year. They typically only had one or two days off in a month.