Do speech marks come after the full stop or before?

Speech marks (also called quotation marks) come before the full stop when the full stop is part of the quoted material.

Here's an example:

* "The cat sat on the mat," she said.

However, if the full stop is not part of the quoted material, it comes after the speech marks:

* She said, "The cat sat on the mat."

Let me know if you'd like more examples!