A working title, sometimes called a production title or a tentative title, is the temporary title of a product or project used during its development, usually used in filmmaking, television production, video game development, or the creation of a novel or music album.
Working titles are used primarily for two reasons – the first being that an official title has not yet been decided upon, with the working title being used purely for identification purposes, and the second being a ruse to intentionally disguise the real nature of a project.
Examples of the former include the film Die Hard with a Vengeance, which was filmed under the title Die Hard: New York, and the James Bond films, which are commonly produced under numerical titles such as Bond 22, until an official title is announced.
A notable example is Disney's The Emperor's New Groove, whose working title is Kingdom of the Sun, with an alternate plotline.
Examples of the latter include Jurassic World, produced under Ebb Tide, Return of the Jedi, which was produced under the title Blue Harvest, 2009's Star Trek, which was produced under the title Corporate Headquarters, and the Batman films Batman Returns, Batman Forever, Batman Begins, The Dark Knight and The Dark Knight Rises, which were produced under the titles Blinko, Dictel, The Intimidation Game, Rory's First Kiss, and Magnus Rex, respectively.
In 2009, the video game Rock Band Network was produced under the code name Rock Band: Nickelback. 
In some cases a working title may ultimately be used as the official title, as in the case of the films Cloverfield, Project X (2012), High School Musical, and Snakes on a Plane (at the insistence of leading man Samuel L. Jackson, who joked that he took the role for the working title alone, after he learned the title was going to be changed to Pacific Air Flight 121 upon release), the television shows The Mindy Project and The Cleveland Show, and video games Quake II, Spore, Silent Hill: Origins and Epic Mickey.
Films in the Marvel Cinematic Universe have been under very inconspicuous titles to prevent spoilers from leaking.
A title ruse is a practice by which a high-profile film or television series is given a fake working title to keep its production a secret, and to prevent price gouging by suppliers, casual theft and undesirable attention. Purchase orders from vendors, outdoor signs, videocassettes and DVD labels will use the cover title of a film.