

The Basics
How you represent character's thoughts depends on whether you are writing in the first person ("I") or third person ("he, she").
We'll focus on prose written in the third person past tense because that is the most common (and few people have any trouble with first-person
thoughts).
Here are your options:
[1] Italicized, present tense, untagged
Janet stared at the shiny car. It's beautiful. I want it.
(The thought is in present tense (in contrast to the past tense of the overall prose) and is italicized but does not have a thought tag.)
Advantages: Leaves little room for reader confusion.
Puts the reader in the character's head. (The thoughts have a verbatim feel.)
Highest emotional impact.
Disadvantages: Becomes visually distracting if your style includes many thoughts.
Conclusion: This is the most universally accepted method.
[2] Italicized, present tense, tagged
Janet stared at the shiny car. It's beautiful, she thought. I want it.
Advantages: Same as "[1]."
Disadvantages: Can sound clunky and repetitive. A better technique would be to plant the thought in a context that renders the tag unnecessary.
Conclusion: This technique is best used in conjunction with [1] for the rare situation where a tag is needed for clarity and recasting isn't an option.
[3] Not italicized, present tense, untagged
Janet stared at the shiny car. It's beautiful. I want it. (The change to present tense/first person signals to the reader that this is a thought.)
Advantages: Lack of italics is less jarring.
Disadvantages: Change in tense (without tag/explanation) can be confusing and can cause the reader to stumble.
[4] Not italicized, present tense, tagged
Janet stared at the shiny car. It's beautiful, she thought. I want it.
Advantages: The lack of italics is less jarring.
Disadvantages: Can sound clunky.
If the tag does not appear early in the thought, the reader may become confused.
[5] Not italicized, past tense, untagged
Janet stared at the shiny car. It was beautiful. She wanted it.
Advantages: Flows seamlessly with surrounding prose (no jarring italics or tense change).
Disadvantages: Thoughts can sound like authorial intrusions.
Thoughts sound like summaries.
[6] Not italicized, past tense, tagged
Janet stared at the shiny car. It was beautiful, she thought. She wanted it.
Advantages: Flows well with the prose (no jarring italics or tense change).
Disadvantage: Thoughts tend to feel like summaries rather than verbatim thoughts. (This pushes the reader away slightly.)
Tag can be clumsy.
So many options! Now what?
Although all of the above options can be used correctly and effectively, I would suggest the following combination of techniques:
For times when the exact thought is important, use technique [1].
Use technique [5] to summarize the characters thoughts.
Beyond the Basics
Syntax
Usage Key
Misuse
Let's Talk Style
Let's see how the pros use it
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