Intercutting or cross-cutting is the name of a technique used in movies to establish action happening at the same time. The camera cuts back and forth between two different actions, which can suggest that these actions are happening at the same time. Cross-cutting can also be used for characters in a film with the same goals but different ways of achieving them.
Suspense may be added by cross-cutting. It is built through the expectations that it creates and in the hopes that it will be explained with time. Cross-cutting also forms parallels; it illustrates a narrative action that happens in several places at approximately the same time. For instance, in D.W. Griffith's A Corner in Wheat (1909), the film cross-cuts between the activities of rich businessmen and poor people waiting in line for bread. This creates a sharp dichotomy between the two actions and encourages the viewer to compare the two shots. Often, this contrast is used for strong emotional effect, and frequently at the climax of a film. The rhythm of, or length of time between, cross-cuts can also set the rhythm of a scene. Increasing the rapidity between two different actions may add tension to a scene, much in the same manner of using short, declarative sentences in a work of literature.
Cross-cutting was established as a film-making technique relatively early in film history (a few examples being Edwin Porter's 1903 short The Great Train Robbery and Louis J. Gasnier's 1908 short The Runaway Horse); Griffith was its most famous practitioner. The technique is showcased in his Biograph work, such as A Corner in Wheat and 1911's The Lonedale Operator. His 1915 film, The Birth of a Nation, contains textbook examples of cross-cutting and firmly established it as a staple of film editing. Mrinal Sen has used cross-cutting effectively in his agitprop film Interview which achieved significant commercial success. Christopher Nolan uses cross-cutting extensively in films such as Interstellar, The Dark Knight, and Inception - particularly in the latter, in which sequences depict multiple simultaneous levels of consciousness. Cloud Atlas is known for its numerous cross-cuts between the film's six different stories, some lasting only a few seconds yet spanning hundreds of years in different locations around the world. Its cuts are eased by the similar emotional tone depicted by each side's action.
Cross-cutting is often used during phone conversation sequences so viewers see both characters' facial expressions in response to what is said.