One of the things you will need to do with your novel is generate a synopsis of it. A synopsis is a short summary of the plot of a work of fiction. You use a synopsis to tell someone what your novel or story is about. That’s the definition of the word.
The function of a synopsis is to sell your story. To sell it to an agent of publisher, you need to include the ending. To sell it to a potential reader, leave that part of the synopsis off. A synopsis can be as long or short as you want it to be. It doesn’t have to be very detailed. Broad strokes are enough if you have a long work to summarize.
A man is visited by three ghosts at Christmas. The ghosts teach the man about the Christmas spirit. That’s a broad strokes summary of A Christmas Carol. That is the kind of synopsis you might want to use in a query letter to an agent or publisher. You’d want to do a bit more detailed synopsis to send with the manuscript to an agent or publisher. It should be between five and six hundred words. Remember, this is NOT the blurb on the back of books, you are selling the novel, not the book. There’s a difference. When you write the text that appears on the back of a book that sells the book. You don’t want to hype the story when writing the synopsis for a publisher. That synopsis is solely to give the publisher an idea of what they are buying.
Writing the synopsis is not easy. Your impulse is to include every detail. Don’t. Just hit the highlights. Answer the questions, what are the stakes for the protagonist? What’s driving the conflict? How does the protagonist overcome the conflicts? How has the protagonist changed over the course of the story? If you can do that, you will have the synopsis. Remember this is a broad summary of the plot. Details are not really required. If you have space in the five or six hundred words, add in the action for a few of the more important characters in the story. You probably can’t include all the characters, so choose the ones to include with an eye to how important they are to the protagonist’s journey though the story.
That’s basically all there is to writing a synopsis for your novel. Remember to include the ending. This isn’t a book report. It’s a tool to sell your work to a publisher. If that’s not your goal, you don’t need to worry about writing a synopsis. If you want to sell your work to a publisher, you’ll need a synopsis. There are places online that can give you more information on how to write them. I’ve only given you the bare bones of the process. It’s important. Don’t neglect it and write it with as much care as you do your actual story. You won’t regret it.