枕，俗称枕头，亦有称头枕（如鲁南部份地区。“头”字读音同“豆”，此为“头”字古音的一种保留）。为睡眠时，壂于头部下方的寝具。

枕头的种类很多，现代常见的有羽绒枕头、中空棉枕、保健枕头等等，而不同种类的枕头有着不同的功效。东亚传统枕头为方形，除了软枕头外还有陶瓷、金属制的硬枕。大致上软枕头可分为三大类，一是填塞枕，如化纤枕，羽绒枕，药枕；二是定型枕，如乳胶枕，记忆枕；三是可调控枕，如智能类枕头，升降枕等。

羽绒枕头已有相当的历史，但至今仍然盛行。据了解，羽绒枕头主要成分以鹅、鸭等的绒毛为主，三角形骨架架构的绒毛，跟随温度的变化而自然地收缩膨胀，这类枕头就容易定型，而羽绒纤维有强力的回复弹力，用一段时间后用力拍打，便会恢复蓬松原状。属于填塞枕头。

A pillow is used to sleep on and other parts of the body, used while sleeping on a bed, or, in the United States, for the body as used on a couch or chair.

In contemporary western culture pillows consist of a fabric envelope which contains a soft stuffing, which may range from down feathers to synthetic foam. In other cultures, pillows have been made of wood or stone. Bed pillows are typically covered with a cloth pillowcase. Pillows used in a living room typically have a sturdy cloth cover.