An outline of a book is basically where you take out a blank document, and you write down the characters that you want to include, you write down their personalities and so on. Then you write what you want to include in chapter 1, 2, 3 etc. and you write out the plot and story of the book.
A lot of people find it better to do that, and schools definitely teach you to do that, but here is why I believe that should not be the case.
It impedes spontaneous creativity
Spontaneous creativity is where you lead your characters to certain places, and not even you as a writer know where they’re going or what is about to happen. So if you as a writer don’t know what’s about to happen, how the heck are your readers supposed to know what’s about to happen?
It keeps your readers on their toes and the unpredictability and suspense factors increase. When something shocking your random happens, it is a surprise to both you and your reader.
You’re making your own book boring to yourself
You will be writing your book anywhere from a month to a year, which is quite a commitment. You are going to be working on it every other day, and revisiting the same story and the same characters will end up feeling tedious and that’s when procrastination and mood drops end up happening.
But ya know what? If you are your own reader of your story and you write the book as it comes to you, it’s no longer boring! One book I wrote (The Portal) I broke a record of the most written words in a single day, which was 14,000 words from morning till night. I wrote all day with only food and tea breaks, because it was just SO darn interesting I wanted to see how it would end!
Most of the big authors do this
This is a bit of a cheat point, but it helps us prove that good art can still be produced without a lot of planning. Author Philip Pullman who wrote The Golden Compass which later got turned into a movie said in an interview that he had no idea when Iorik the Bear (a main character) would appear and when it did it was a major turn of events for the whole story. The whole story got changed based on spontaneous creativity!
Essentially, your characters discover the world and meet new people and the CHARACTERS don’t know anything yet and they themselves figure out as the story uncovers. The same goes for your readers, who find things out alongside your characters. And the same can apply to the authors, which ensures fluidity of mystery and does not seem like it is leading to something predictable or obvious.