Interior monologue is the fancy literary term for a character's thoughts in a novel.
In real life, the stream of thoughts we all have running through our heads at any given moment is more often referred to as internal monologue, though the two terms mean precisely the same thing.
While we are dealing with definitions, a couple of closely-related literary terms are...
The ability of readers of fiction to hear a character's thoughts directly is one of the huge advantages of novels and short stories.
You can't hear what is going on inside a movie character's head.
You can't hear a person's thoughts in real life, either, unless of course they voice them out loud. (Even then, you don't know if they are being altogether truthful.)
Sure, you can guess what a person is feeling and thinking inside by their body language, their facial expressions, and so on. But the only time we get to hear another person's thoughts word for word is when we read interior monologue in a novel or story.
This ability to experience what life is like inside a fictional character's head, hearing everything they think and feeling everything they feel, is one of the main reasons people read fiction.
When movies were invented, it was supposed to mark the beginning of the end of novels. The same thing was true when television came along a few decades later. But it never happened.
People continued to read novels and they probably always will.
Now, I am not arguing that written fiction is superior to fiction on the big and small screens, because films and television clearly hold many advantages over books. But books have their advantages as well, and I would suggest that the three biggest ones are...
The third of these advantages is, I believe, the fundamental reason why written fiction will never die. Put simply, you can establish a far more intimate relationship with a character in a book than a character on a screen.
Sometimes, you even lose your heart to a character in a favorite novel.
And it is all because you have direct access to what that character is thinking.
All of which is a long way of saying that interior monologues matter. Thoughts are important in written fiction because it is the only place you can find them, so if you are planning on not making much use of what is going on inside your protagonist's head and writing in a more distant and cinematic style, think again.
Interior monologue is one of the best tools in your toolbox.
Don't worry, I'm not about to blind you with science. The two varieties of monologue found in a novel are...
And that is about as complicated as it gets. But for a fuller explanation, complete with examples, check out The Two Types of Monologue.
Everything I have said about internal monologue so far has been useful (I hope!) but still kind of vague. What many novel writing beginners want to know is precisely how to portray a character's thoughts on the printed page - should they use italics, for example, or a "he thought" tag?
This article on the mechanics of internal monologue addresses these issues.
So what is the best way to indicate that a sentence or two of interior monologue in the middle of a scene is the viewpoint character's thoughts (and not the narrator narrating)? The following articles explain all...
In Internal Monologue Mechanics, I look at the range of options open to you for how to present a character's thoughts to the readers. And in these articles, I delve deeper into a couple of key issues...
If you don't want to read the articles right now, I can offer this general advice...
Whatever method you choose to present a character's thoughts to the readers, use it consistently. If you italicize the interior monologue in chapter 1, for example, stick with it to the end.
And regarding monologue "tags", the best advice is to only use them when you wish to make it clear that the character is thinking.
Generally speaking, you will need to do this most during the "cooler" opening section of a scene. Once the scene has "warmed up" and we are deeper inside the viewpoint character's consciousness, the fact that they are thinking these words is usually obvious.
Also, try to make the actual words that a character thinks more lively and direct as the scene develops.
For example, at the start of a scene you might write a couple of sentences of interior monologue like this...
If the scene had already warmed up, though, you might choose to drop the tag and write something like this...
Pretty much everything I have said up to now about interior monologue applies to third person point of view novels written in the past tense. (This is by far the most common form of voice and tense used by writers.)
In a third person, present tense novel, it is literally just a case of changing the past tense to present. So instead of writing this...
You write this...
Simple. In a first person novel, whether written in the past tense or present tense, interior monologue is easier still. Why? Because it happens naturally, all by itself.
The biggest challenge you face in a third person novel is making it clear that the words are indeed the character's thoughts, and not the narrator's words.
That is why, when the viewpoint character is being viewed from a distance, you might use a thought tag to make it clear that these words are indeed the character thinking, and only drop using tags once the camera has moved behind the character's eyes, so to speak.
But in a first person novel, the camera is always behind the character's eyes, and so it is obvious when we hear their direct thoughts. Like here...
There is nothing to stop you using a thought tag here ("The summer had been so perfect, I thought...") but it really isn't necessary. It is obvious that the character is thinking these thoughts in the here and now of the story.
The only thing you need to bear in mind (and this is quite a technical point I am making) is that there is a subtle but important difference between...
(If this concept is completely unfamiliar to you, please review the article on First Person Theory in the Point of View section.)
The viewpoint character and narrator in a first person novel are both the same person, of course, but they are at different stages in their life. The narrator is the older person writing the story after the events are over, while the viewpoint character is the younger person actually experiencing the events as they happen.
How do you reflect these two different selves in interior monologue? In precisely the same way you would do it in a third person novel...
Now, in a novel in which a forty-year-old narrator is writing about an event that took place last year, there isn't going to be much difference between their older and younger voices (save for the fact that the slightly older narrator will have been changed by the novel's events, whereas for the viewpoint character the transformation still lies in the future).
But if the narrator is forty and the viewpoint character is fourteen, the difference in their voices will be huge.
I appreciate that this is a subtle point I am making, but it is only by giving full care and attention to the little things that you will become a master of interior monologue in particular and novel writing in general.