Most filmmakers know scripts follow a very particular format, but do they know why they do?Thanks to all of the low-cost/free screenwriting programs that are available nowadays, writers don't have to think too hard about formatting when penning scripts. However, understanding what all of the different formatting components are, like slug lines and action, as well as why they're formatted the way they are is important for making sure that your story is not only organized and clear but that it adheres to industry standards. This video from StudioBinder helps demystify many of the basic formatting rules as well as several obscure ones in screenwriting. Check it out below:
Again, screenwriting software like Final Draft, Celtx, and WriterDuet make it easy to not concern yourself with script format too much, but it's still important to learn. You may not have to worry about margins, typeface, or indentations, but you'll still need to know how to write action, dialogue, as well as what a slug line is and why the information included in it is so important.
Because even if you understand everything that's going on in your screenplay when it comes to formatting, there will (hopefully) be other people looking at it that may not. Remember, if your script gets selected to be turned into an actual film, it will need to be turned into a script breakdown sheet. So, if you don't take care being clear and concise with your slug lines, action, and dialogue then the director, DP, and 1st AD will have a hard time doing their job.
Luckily, screenplay formatting isn't rocket science. It just takes a little effort to wrap your head around several key concepts and elements...and once you do, you're off to the races.