First aid is the provision of limited care for an illness or injury, which is provided, usually by a lay person, to a sick or injured patient until definitive medical treatment can be accessed, or until the illness or injury is dealt with (as not all illnesses or injuries will require a higher level of treatment). It generally consists of series of simple, sometimes life saving, medical techniques, that an individual, either with or without formal medical training, can be trained to perform with minimal equipment.

First aid can also be performed on animals, although this article refers specifically to human first aid.