A close-up is a framing technique used by a director to place all focus on a particular character within a scene. When a character is framed in a close-up, the background of the scene is hardly visible. Extreme close-ups eliminate the background altogether, placing all focus on a character's face. Sometimes, only aspects of the face --- such as the eyes --- are within the frame. A medium close-up reveals more of the background, but the focus is still on the character in question as he digests a situation, information or environment. Both a medium close-up and a close-up are used during the Omaha invasion scene in "Saving Private Ryan." Within that scene, Tom Hanks is framed close, allowing the audience to experience the horrors of war through his facial expressions.
While a character can be framed in the foreground, directors often leave enough space in the background for action to develop. Oftentimes, the character --- or characters --- will inhabit one side of the screen while action develops behind her. This technique is often used in slapstick comedies, such as "The Naked Gun," in which characters in the foreground communicate while a comedic episode develops behind them. However, this technique is not reserved for comedies alone. For example, horror films often frame a character to one side of the screen while the villain --- or monster --- inhabits the background of the scene, quietly approaching from behind.
A montage is used within a film to show a passage of time. Framing within the montage can be utilized to show a change in character attitude. The breakfast table montage in "Citizen Kane" uses framing to show the dissolution of a marriage. As the montage begins, Kane and his wife are framed in a two-shot (both characters are visible in the shot). This framing indicates a healthy marriage. As the montage continues, the two-shot is replaced with alternating medium shots, never showing the two characters within a single shot. The final shot is a wide shot, and the framing shows Kane and his wife at opposite ends of a long breakfast table. This indicates that their marriage is coming to an end.
Framing a character with a wide shot accomplishes two tasks: showing off the environment around him, and giving the audience a sense of that character's place in the world. A wide shot is used during the opening of "Vanilla Sky" as Tom Cruise runs around an empty Times Square in New York. The wide shot allows the audience to view the emptiness of the usually crowded environment. The camera pulls back even wider, symbolizing Cruise's isolation and confusion. A wide shot can also be used to frame multiple characters within a single location, allowing the audience to recognize who the main characters are and what environment they dwell in.