"4-D film (sometimes written as 4D film) is a marketing term that describes an entertainment presentation system combining a 3-D film with physical effects in the theatre, which occur in synchronization with the film (note that 4-D films are not actually 4-dimensional). Because the physical effects can be expensive to install, 4-D films are usually presented only at special venues such as theme parks and amusement parks. However, in Mexico, Nepal, South Korea and India, some movie theatres also have the ability to present a 4-D film and the film Avatar was one of 10 films that have received the treatment, starting with Journey to the Center of the Earth.[1] Some of the effects simulated in 4-D films include rain, wind, strobe lights, and vibration. The use of water sprays and air jets is also common. A 4-D film is not shown in a motion simulator, although some seats in 4-D venues vibrate or may move a few inches during the presentation."