The lap is the upper side of a seated person's thighs, between the knees and the waist. Since it is horizontal, muscular and strong, it can comfortably support a weight that rests on it, such as the weight of another person. Children, in particular, like to sit on an adult's lap for all kinds of things, whether it's some activity such as eating, being told a story, or cuddling. This expresses trust and affection. Children sitting on Santa Claus's lap in a shopping mall are a stereotypical example, as is the Christian depiction of Mary with infant Jesus sitting on her lap.
There are four basic ways to sit on someone's lap:
- facing another (straddling)
- facing the same direction, legs together
- facing the same direction, straddling
The person whose lap is used will usually hold and thus stabilize the sitting person with his or her arms. The person whose lap is used may be sitting on a chair or similar furniture, or may be sitting or kneeling on the floor. It is also possible to lie on someone's lap, to rest one's head in someone's lap, or to lie over someone's lap.
The same that is popular with parents and children is also popular with lovers.
 The lap in spanking
In several spanking positions, the spankee lies on or over the spanker's lap. The best known example is the over-the-knee position. Variants are the frontal over-the-lap position, the over-one-knee position, and the straddling position. It is even possible to take two (small) spankees over the lap at the same time, see two spankees OTK.
Spanked over the lap of a kneeling person, illustration by Gauis Marius (2007).
 See also