An air mattress or airbed is an inflatable mattress or sleeping pad that can be pumped up by an electric pump, or manually by a hand or high volume bellows foot pump via attaching the hose into the air valve.

Due to its buoyancy, it is also often used as a water toy or flotation device, and in some countries, including the UK and South Africa, is called a lilo ("Li-lo" being a generic trademark — derived from the phrase "lie low") or a Readybed.

An air mattress, also known as an airbed or a blow-up bed, is an inflatable mattress made of polyvinyl chloride (PVC) or textile-reinforced urethane plastic or rubber. The deflated mattress can be compacted and carried or stored in a small form. They are inflated by blowing into a valve, either with a manual or an electric pump. Some are automatically inflated when a valve is opened, up to a certain pressure with additional inflation manually or by pump.

Air mattresses are used for camping, temporary or full-time home use, and may be optimized to combine several uses (e.g., camping and guest use) while others are single purpose. Air mattresses may have customized shapes, such as wheel cutouts for use in the cargo area of a pickup truck or SUV.

Sleeping pads are lightweight, reduced-size and reduced-thickness air mattresses intended for camping and backpacking, and may feature a layer of foam insulation under the air chambers. Higher quality air chambers use vulcanized rubber, covered in canvas or of polyurethane with a cloth shell or tick(ing). Permanent air beds will look almost like conventional beds with the exception of having a hose (one air chamber) or hoses (two air chambers) coming out of the head of the bed. These hoses will be connected to an air inflation device, with two outlet valves, that will have a remote control(s) so that each person can adjust the firmness of his or her side to his/her own exact needs. The firmness can be adjusted up or down, with the simple push of a button, on the remote(s).

A USA government safety agency has warned against letting infants sleep on air mattresses, because they can be too soft and suffocate smaller children (especially those below the age of 8 months) within folds or while entrapped between the mattress and the bed base. Additionally, there have been several recent governmental studies and regulations enacted due to the poisonous nature of the phthalate plasticizers contained within most PVC vinyl air beds and other soft vinyl products. The European Union has made similar efforts to prevent the use of vinyl materials in toys and bedding.

Larger, more elaborate air mattresses (known as "air beds" in British English speaking locations) have come on the market in recent years that are intended for guest use or as permanent beds in the bedroom. Bed sizes for temporary air beds range from twin to king size, but few guest bed manufacturers offer king size as most guest air beds are sold outside the United States where king-size mattresses are not standard. Most permanent air beds use easy-to-find conventional sheets and bedding. California King (or Western King) sheets and bedding may be more difficult to find as this size was originally conceived for the waterbed industry.

Raised guest or temporary beds are typically raised off the ground to keep users away from the floor and offer a more traditional mattress experience. Though 'raised' air beds are off the ground, they are not designed for full-time use, as the base of the bed is an air chamber and not a solid foundation.