Advanced Photo System (APS) is a film format for still photography. The film is 24 mm wide, and has three image formats:

• H for HDTV 16.7 x 30.2 mm ratio 9:16
• C for classic 16.7 x 25.1 mm ratio 2:3
• P for panoramic 9.5 x 30.2 mm ratio 1:3

The two formats beside the H are formed by cropping. The C format is equivalent to the 135 film image aspect ratio. APS cameras support all three formats, and the format can be selected for each image.

The film is on a polyethylene naphthalate (PEN) base, and is housed in a single spool 39 mm long plastic cartridge. The basic diameter is 21 mm, while it measures 30mm at the slot where the film exits. The slot is protected by a lightlock door. It comes in lengths for 40, 25 and 15 exposures. The film surface is coated by a transparent magnetic coating, and the camera uses this information exchange (IX) system for recording information about each exposure. The camera handles winding and rewinding automatically, to the extent that part recorded films can be removed and used later. Numbered symbols on the cartridge end indicate the status:

1. Full circle: Unexposed
2. Half circle: Partly exposed
3. Plus sign: Fully exposed but not processed
4. Square: Processed

Processed (developed) film is stored in the original cartridge. To identify them, every roll of APS film has a six-digit ID code on the label, which is also stored magnetically. The ID is usually printed on the back of every individual print.

To facilitate automatic processing of film, a unique DX number is assigned to the different types of film.

The format was introduced in 1996 by Kodak, Agfa, Fujifilm, Nikon, Canon and others. It is mainly used for point and shoot amateur cameras. The APS film surface area is 56% of 135 film.

Whilst APS SLR cameras appeared, they were never particularly popular in the high-end amateur market who preferred to stick with their 35mm cameras. Low-end compact cameras also stuck with the 35 mm format. As of 2003, the mid-range amateur film camera appears to be gradually disappearing as it is replaced by digital photography, and with it the APS format.