A fragment is part of a sentence?

That's right! A fragment is a part of a sentence that does not have both a subject and a verb. It's like a piece of a puzzle that's missing some important parts.

Here's an example:

* Complete Sentence: The cat sat on the mat.

* Fragment: On the mat. (Missing the subject, "the cat")

Fragments can be grammatically incorrect and confusing for readers. They are often used intentionally in creative writing to create a certain effect, but in formal writing, it's important to make sure all your sentences are complete.