A screenplay (or play or script) is typically made up of scenes. Scenes are made of shots. Scenes make up Themes and Acts. Acts make up a story. One page of script is roughly one minute on screen. There's some give and take depending on action and pacing, but the general rule of thumb is a minute a page.
A screenplay will start with a title page, usually identifying the story name and author. The story typically starts with "FADE IN:". Back in the day, this is how films started, with a subtle fade in from black to the action or opening credits.
The next major element you'll see is a Slugline. This contains three main pieces of information. Is the scene inside, (INTERIOR or INT.), outside (EXTERIOR or EXT.), or both (I/E). The next item is the location, and third is time of day. These are necessary to know where things happen and what locations the crew will need to get. The science of shooting is different for an outdoor shot than in indoor shot. In my stories, I will try to format them in BOLD ALL CAPS.. The Slugline will be aligned left.
Action is the next element. This shows us what is happening on screen. It could be a man walking, a gunfight, a lover's quarrel, anything. I will typically break the action up by shot. If I think that there should be a shot change in the scene, such as a change in point of view or in emphasis, the action will be split into separate lines. This makes it easier for the director (you, since you're reading the screenplay) to imagine the story in the way it was meant to be seen. This is left aligned.
The next elements are the most important part of films for nearly 100 years, and that's dialogue. Dialogue comes normally in two parts, but can also include a couple sets of instructions in parentheses. The CHARACTER speaking will be in ALL CAPS and centered. If there is a set of parentheses to the right, this indicates a special location of the dialog. This is called an Extension. O.S. stands for off screen. This is used when we hear a voice in the scene but don't see them. Another common one is V.O. for Voice Over. This is often a narrator telling a story where they are either not in the scene, or remembering it in a flashback. If there is an instruction in a parentheses under a name, this is called a parenthetical. These are special instructions for the actors to tell them how they should say that line. Actors don't like being told what to do all the time, but good direction keeps the story flowing. Finally, the lines under that are the actual dialogue. This is what the actor says. I will try to format these centered aligned, but I'm still working on cleaning this up. In a traditional screenplay, the dialogue is constrained inside margins. Still figuring that part out here.
Most screenplays consist of these, but can also include other elements. Shot directions will typically tell the viewer when the camera is taking a specific shot, like a point of view or a closeup on an item. Transitions like "FLASHBACK TO:" are common for indicating a time change. "MONTAGE" will show a series of shots, typically with little to no dialogue to demonstrate the passage of time. Subheaders can be used to illustrate simple location changes, like going from a bedroom to a hallway and back again. INTERCUT can be used to show a back and forth between two locations without writing out the entire scene and slugline.
Finally, capitalization is used in various ways. When a character is introduced for the first time, they are typically ALL CAPS. This tells the Director that a new character has been introduced and they need to hire another actor. Sound effects often get this treatment as this indicates that the effects and sound crews will need to work on this. BANG BANG BANG isn't just for dramatic effect, but to tell the various departments how to set this up.
If you want to try your hand at writing, there's many programs out there designed for this, plus extensions and macros for every word processor out there. I started with an extension for Word before splurging a few years back on a new copy of Final Draft. You do not need to spend any money to do this. I did this as a treat for myself.
Below is a sample of a scene I wrote.
INT. HIGH SCHOOL HALLWAY - EVENING
Mark and Mia arrive at the last room for the night, belonging to Ms. Rebecca Hastings. Mark and Mia are about to walk into the room when they hear the conversation inside get elevated.
KAREN (O.S.)
(shouting)
This is completely unacceptable! I’ll have your job for this!
REBECCA
I understand you’re upset, but the school-
(shouting)
This is completely unacceptable! I’ll have your job for this!
REBECCA
I understand you’re upset, but the school-
KAREN (O.S.)
(shouting)
Upset doesn’t begin to describe this! You are a disgrace as a teacher and should be working at Walmart, not at this school.
INT. MS. HASTING'S ROOM - EVENING(shouting)
Upset doesn’t begin to describe this! You are a disgrace as a teacher and should be working at Walmart, not at this school.
Mia leans in to see what’s going on, but Mark pulls her back, only to walk quietly into the room. Mia follows.
The classroom is spartan, aside from a few posters preaching modern Christian ethics, one or two hand-made posters describing various passages from the Bible, and a couple posters talking about how great abstinence is. In the front of the class a married white couple in their 50’s sit facing a teacher’s desk. The couple look like, well, a typical Ken and Karen. He’s balding, wearing a polo shirt and khakis while she’s in an overpriced workout suit and a dyed haircut that screams ‘I-want-to-speak-to-your-manager.’
KAREN
(shouting)
When we are done with you, you’ll be lucky to get a job as a barista at Starbucks! How dare you do this!
The woman Karen is yelling at is the teacher, Rebecca Hastings. (shouting)
When we are done with you, you’ll be lucky to get a job as a barista at Starbucks! How dare you do this!
REBECCA
Ma’am, you need to understand that this school has a very strict policy against plagiarism. It’s not just that your son cheated on his creative writing assignment, but how he cheated. He tried to pass off the first chapter of ‘Paradise Lost’ as his own original work. Then, he decided it would be funny do the same with the Marquis De Sade’s ‘Justine’, but replaced the main character’s name with mine.
KAREN
(shouting)
How dare you accuse-
Rebecca stands up from her seat, keeping her hands on her desk.Ma’am, you need to understand that this school has a very strict policy against plagiarism. It’s not just that your son cheated on his creative writing assignment, but how he cheated. He tried to pass off the first chapter of ‘Paradise Lost’ as his own original work. Then, he decided it would be funny do the same with the Marquis De Sade’s ‘Justine’, but replaced the main character’s name with mine.
KAREN
(shouting)
How dare you accuse-
REBECCA
How dare you, come into my classroom, threaten my job, my career, because you failed as a parent and raised a cheater. You should count your blessings that he wasn’t expelled.
Mark stops in his tracks when he sees her for the first time. She looks like she’s in her mid to late-20’s, and is an absolute stunner. How dare you, come into my classroom, threaten my job, my career, because you failed as a parent and raised a cheater. You should count your blessings that he wasn’t expelled.
Her blonde hair comes down to her shoulders, and even in conservative dress of a button-up blouse and pencil skirt, he can tell she takes great pride in her body and diligently works out.
Karen gets inches from Rebecca’s face. Ken, for his part, does nothing but sits in his chair.
Hope this helps. Please ask any questions, and I'll try to answer them.
EDIT: See below for notes on formatting changes as we go.
