Do you need speech marks when someone is thinking?

You don't need speech marks when someone is thinking, but you do need to use some kind of indicator to show that it's a thought. Here are the common ways to do that:

* Italics: This is the most common way to indicate thoughts in writing.

* Example: *I wonder what she's doing here,* he thought.

* Parentheses: You can also use parentheses to indicate thoughts. This is less common than italics.

* Example: (I wonder what she's doing here), he thought.

* Dashes: Dashes are another option, often used in dialogue to show interrupted thoughts.

* Example: "I think...– wait, is that what I think it is?"

It's important to be consistent with your choice within a piece of writing. If you choose italics for thoughts, stick with that method throughout.