IMAX is a motion picture film format and projection standard created by the Canadian IMAX Corporation. The Company’s activities include the design, leasing, marketing, maintenance and operation of IMAX film and digital theatre systems as well as the development, production, post production and distribution of IMAX motion pictures.

IMAX has the capacity to record and display images of far greater size and resolution than most conventional film systems. A standard IMAX screen is 22 × 16.1 m (72 × 52.8 ft) and they are generally the same everywhere. IMAX theatres are described as either "Classic Design," (Purpose-built structures designed to house an IMAX theatre) or "Multiplex Design." (Existing multiplex auditoriums that have been retrofitted with IMAX technology). The world's largest cinema screen (and IMAX screen) is in the LG IMAX theatre in Sydney, New South Wales. It is approximately 8 stories high, with dimensions of 35.73 × 29.42 m (117.2 × 96.5 ft) and covers an area of more than 1,015 m (10,930 sq ft).

IMAX is the most widely used system for special-venue film presentations. As of December 2009, there were more than 400 IMAX theatres in over 40 countries. Imax Corporation has released four projector types that use its 15-perforation, 70mm film format: GT (Grand Theatre), GT 3D (dual rotor), SR (Small Rotor), and MPX, which was designed to be retrofitted in existing multiplex theatres. In July 2008, the company introduced a digital projection system, which it has not given a distinct name or brand, designed for multiplex theatres with screens no wider than 21.3 m (70 ft). A presentation that is digitally projected is nonetheless represented to be IMAX, contrary to the extent of trademarks registered with the U.S. Patent and Trademark Office.

All IMAX projectors, except the standard GT system, can project 3D images.

Most IMAX theatres have flat, rectangular screens, but IMAX Dome theatres, formerly branded as OMNIMAX, use a GT projector with a fish-eye lens to project an image on a tilted hemispheric dome screen. Imax also has a special simulator technique which uses seat movement/vibration at specific points in the film.