Interior- or inner monologue is a technique authors use for several reasons, usually related to characterization. Using either first- or third person limited point of view, the author makes clear what a character (typically the protagonist) is thinking or feeling.
Sometimes interior monologue reveals a character's unspoken thoughts, and often authors will italicize those words so that readers can visually separate the interior monologue from the rest of the text or conversation. It would look something like this:
Mrs. Smith asked if anyone was interested in doing the extra credit.
It's gonna take a lot more than 5 points to help my calculus grade, lady. Smiling, I said, "I'd love to do it, Mrs. Smith."
Sometimes interior monologue can be used to reflect how a character feels about himself or herself. Consider a girl getting ready to go out on a date:
The doorbell rang. Don't answer too quickly. You'll look desperate. Walking to the door, Skyler reconsidered her outfit. This is over the top. Too...
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