P.S. stands for postscript, which comes from Latin words meaning “written after.” It's the part of a letter or message that comes after your signature, when you suddenly remember something you forgot to include.

You might write a thank-you note to your grandmother, sign your name at the bottom, and then realize you forgot to mention something important: “P.S. I loved the cookies you sent!” The P.S. lets you add that extra thought without rewriting the whole letter.

Before computers and delete keys, if you were writing by hand and remembered something after finishing, you had two choices: start over completely or add a P.S. Even though we can easily edit messages now, people still use P.S. in emails and texts. It's useful for adding something that feels separate from your main message, like a quick reminder or an afterthought.

Sometimes people even add a P.P.S. if they think of yet another thing to mention. Writers occasionally use P.S. strategically too, knowing that the last thing someone reads can stick in their memory. That little addition at the end can be surprisingly powerful.