A screenplay or script is a blueprint, written by a screenwriter, for a film or television program. Screenplays can be original works or adaptations from existing works such as novels. A screenplay differs from a script in that it is more specifically targeted at the visual, narrative arts, such as film and television, whereas a script can involve a blueprint of "what happens" in a comic, an advertisement, a theatrical play and other "blueprinted" creations.
The major components of a screenplay are action and dialogue, with the "action" being "what we see happening" and "dialogue" being "what the characters say". The characters, when first introduced in the screenplay, may also be described visually. Screenplays differ from traditional literature conventions in ways described below; however, screenplays may not involve emotion-related descriptions and other aspects of the story that are, in fact, visual within the end-product.
For more details on the contents of screenplays, see Screenwriting.
In the United States, the Writers Guild of America (WGA) has final control on who may be awarded screenwriting credit for a screenplay in a union production. The WGA is one of several organizations in the U.S. and worldwide which recognize screenplays with awards.
A script for television is sometimes called a teleplay.

Screenplay format
Motion picture screenplays intended for submission to mainstream studios, whether in the US or elsewhere in the world, are expected to conform to a standard typographical format known widely as studio format which stipulates how elements of the screenplay such as scene headings, action, transitions, dialog, character names, shots and parenthetical matter should be presented on the page, as well as the font size and line spacing.
One reason for this is that, when rendered in studio format, most screenplays will transfer onto the screen at the rate of approximately one page per minute. This rule of thumb is widely contested — a page of dialog usually occupies less screen time than a page of action, for example, and it depends enormously on the literary style of the writer — and yet it continues to hold sway in modern Hollywood.
There is no single standard for studio format. Some studios have definitions of the required format written into the rubric of their writer's contract. The Nicholl Fellowship, a screenwriting competition run under the auspices of the Academy of Motion Picture Arts and Sciences, has a useful and accurate guide to screenplay format. A more detailed reference is The Complete Guide to Standard Script Formats (Cole and Haag, SCB Distributors, 1980, ISBN 0-929583-00-0).
Traditionally, a screenplay should be 90-110 pages long. Comedies and children's films tend to weigh in at the lower end.
Screenplays are almost always written using a monospaced font, often a variant of Courier although other fonts are sometimes seen, including those intended to resemble the output of an old battered typewriter such as a Remington Portable.

Television
American screenplays are printed single-sided on three-hole-punched letter sized (8.5 x 11 inch) paper, and held together with two brass brads in the top and bottom hole. The middle hole is left empty. In the UK, double-hole-punched A4 paper is often used, although some UK writers use the US letter paper format, especially when their scripts are to be read by American producers, since otherwise the pages may be cropped when printed on US paper. Despite the use of double-punched paper, it is common to see scripts in the UK held together by a single brad punched in the top left hand corner. This makes it easy to flip from page to page during script meetings and may have something to do with the taller page of A4.
Screenplays are usually bound with a light card stock cover and back page, often showing the logo of the production company or agency submitting the script.
Increasingly, reading copies of screenplays (that is, those distributed by producers and agencies in the hope of attracting finance or talent) are distributed printed on both sides of the paper (often professionally bound) to cut down on paper waste out of environmental concerns. Occasionally they are reduced to half-size to make a small book which is convenient to read or put in a pocket; this is generally for use by the director or other production crew during shooting.
Although most writing contracts continue to stipulate physical delivery of three or more copies of a finished script, it is common for scripts to be delivered electronically via email. Although most production companies can handle scripts in most formats, it is better practice to supply scripts as a PDF file where possible. This is because it gives the writer final control over the layout of the script, which may otherwise vary depending on what fonts and/or paper size the recipient uses to print the script out. The formatting software programs listed at the bottom of this article produce industry formatted standard screenplays in PDF.

Physical format
Screenplays can be written either on "spec" (speculative) or as assignment ("Commissioned"). The Variety slanguage dictionary defines "spec script" as "a script shopped or sold on the open market, as opposed to one commissioned by a studio or production company."

Writing on spec or assignment
Assignments are commissioned by production companies or studios on the basis of pitches from producers or writers, or literary properties they already own. Most established writers do most of their work on assignment and will only "spec" scripts which they think no-one will pay them to write, or if they cannot find assignment work.
There are exceptions: some very famous writers only write on spec because they know that they can get a better price for their work this way. Other writers spec scripts that they care deeply about so that they do not have to bend to the whims of executives and producers.
An assignment may be for an original screenplay, or for an adapted screenplay based on another work such as a novel, film, short story, comic book, magazine article or, increasingly, video game. It may also, however, be for a rewrite of an existing script, and in fact this is how a large proportion of writers in the modern studio system make their living. Rewriting scripts is an art in itself and an extremely lucrative one at that: it is not unknown for trusted writers in the higher echelons of the industry to receive $200,000 a week (2004 numbers) for their efforts. $50,000 per week is not uncommon.
Rewriting is difficult because executives often have very clear ideas about what is wrong with a script, however, they are usually unable to provide detailed prescriptions for ways it can be fixed. This is not surprising, because screenwriting is not the expertise of the executive, but of the screenwriter. The writer is therefore usually expected to come up with a detailed prescription for how the script can be improved, and then execute this in a timely fashion. During the process of choosing a writer to rewrite a script the executives may ask several writers for their 'take' and choose the one who appears to have the greatest likelihood of moving the script forward to the point where it may be greenlit for production.
Before 'going to script' a writer may be asked to write a treatment, an outline, or a step outline describing the script in various granularities of detail. Some writers resist this process and will do anything to avoid it and get down the writing the script itself; others embrace the process and even deliver fairly elaborate treatments, the so-called scriptments. It is fair to say that producers tend to be wary of the former and pleasantly surprised by the latter.

Writing on assignment

Main article: Spec script Spec scripts
Script costs can include adaptation rights, but often story rights are listed separately in the development section of a budget.
The cost of screenplays varies enormously, and there are often many different writers involved, some of which are uncredited. For example, Quentin Tarantino did uncredited rewrites for Silver Surfer and It's Pat (see Jami Berhard's Quentin Tarantino: The Man and His Movies).
Jurassic Park was adapted by the book's author, Michael Crichton, for a large undisclosed sum. His salary for Twister was 2.5 million, but there were many writers involved, not just him.
Out of a $72 million budget for the film Signs, writer-director M. Night Shyamalan was paid $5 million, most of which were however license fees for the story rights. For the film The Village (total budget: $71 million) Shyamalan received $327,500 for all writing costs including the screenplay fees for his production company Blinding Edge Pictures and costs for materials, supplies, script duplication as well as fringes. An additional $7.2 million were payed to Shyamalan for the story rights, almost three times the amount Shyamalan earned for his work as producer and director on the film.
Although the highest paid names are stars and directors and sometimes novelists who get their novel adapted, a good screenwriter can command - and is worth - a large salary.
Total script costs can easily be ten percent of the film's budget but, like other areas of a film, unless the writer is a star, it is unlikely for a big budget film to spend more than 5% in the script department.
For a movie with a script budget of $500,000 that is not an adaptation, written on assignment, the payments might break down as follows (referred to as "300,000 against 500,000"):
The first four payments are paid half on commencement of the writing step and half on completion. The final payment, the production bonus, is paid only if the script goes into production and becomes due on the first day of principal photography. If a script is approved for production before all the steps have been completed, the production bonus could be bigger. This means there may be an incentive for the writer not to drag out the process.

First draft: $150,000
First draft revisions: $50,000
Second draft: $75,000
Second draft revisions: $25,000
Production bonus: $200,000 Script costs
Once a studio has purchased or commissioned a script, it goes through the process of revisions and rewriting until all stakeholders are satisfied and ready to proceed. It is not uncommon for a script to go through many, many drafts on its journey to production. Very few scripts improve steadily with each draft, and when a certain avenue has been exhausted the writer will often be replaced and another brought in to do a rewrite.
Occasionally it becomes impossible to satisfy all such parties, and the project enters development hell.
If a studio decides it does not wish to proceed to production with the script, the project enters 'turnaround'. Another studio may purchase the script from its original owner, but the script is encumbered with the development costs the studio has already incurred. At a certain point, it may simply be uneconomic for anyone to purchase the script, even if it is a very good one. This goes part of the way to explaining why some of the best scripts in Hollywood remain unproduced.

The development process

Main article: Shooting script The shooting script
A screenplay is different from a transcript. A transcript is simply a copy of what dialogue finally appeared onscreen, without regard to the original script, the stage directions or action. A full post-production transcript may also include descriptions of the action on-screen, but since it is generally not written by a professional writer but either a production assistant or a fan, it may not be particularly entertaining to read.
Many published screenplays available at booksellers or downloaded from the internet are in fact glorified post-production transcripts rather than shooting scripts. Transcripts and screenplays often differ radically because scenes are frequently re-ordered or dropped entirely during the editing process. Moreover, actors may change lines or simply improvise dialog, and many directors will make their own changes to the script on the fly during rehearsal or shooting.
It can be extremely revealing to compare a shooting script with the film as finally distributed.

Screenwriting software

Screenwriter's salary
Screenwriting
Storyboard
List of motion picture-related topics
Guide to Literary Agents
Writer's Digest
Act structure (Film)