Theater or Theatre:  place for seeing.  Depending on your geographic location will determine your likely spelling.  Regardless, this is a division of the performing arts.  Although any ‘performance’ could be considered theatre, as a performing art, it focuses almost solely on live dramatic performers. Since it’s the beginning, theatre has taken on many forms combining the other performing arts, such as music and dance into a single performance.
The phrase ‘Going to the theater’ can be associated with the rich.  As it can be quite expensive and is something people look at as high society.  However, going to the theater does not have to be expensive.  There are plenty of community theater groups that put on fabulous productions in what is called ‘Off Broadway’ theaters.  This just means that the actors and actresses aren’t paid much, if anything.  They are there because they love being in the theater.  Some might say that these performances are even better because of their love of the arts, not money.
Movie theaters came along in the late 1800s.  This became an entirely different type of theater experience.  Most movie theaters are commercial operations for the general public.  The film is projected onto a large projection screen.  Motion pictures, in the beginning, had no sound.  In today’s world, the movie theaters are equipped with incredible sound systems as well as the ability to view the movie in a three dimensional (3-D) format.  3-D film is a system of presenting film images so that they appear to the viewer to be three-dimensional. Special glasses are provided to the guests to wear while watching the film.  Three dimensional films use two images channeled, respectively, to the right and left eyes to simulate depth by using 3-D glasses with red and blue lenses. 3-D glasses deliver the image to the eyes and make the image appear to "pop-out" at the viewer and even follow the viewer when he/she moves in order for viewers to see relatively the same image. "4-D" techniques are also used when certain effects such as spraying of water, movement of seats, and other effects are used to simulate actions seen on the screen. t 3-D films were first presented in the 1920s. Today, films are again being presented in cinemas in a 3-D format, in the IMAX 3D system and in digital 3-D, such as are used in the some animated films.  IMAX is a system using film with more than ten times the frame size of a 35mm film to produce superior image quality to a regular film. There is an oversized screen used in IMAX theaters as special projectors.
Going to a theater to view a play or a film can be a wonderful way to expand your mind as well as a place to get lost in another world.  The theater opens up a cornucopia of subjects from love to politics to documenting a true story of a bad diet.  The theater has become a form of communication of subjects, that some folks would never have explored otherwise.