Meaning of the verb register in context

Question

It's form the first episode of the eight season of Friends. Here is the context:

Phoebe: Calm down. Maybe you’re not pregnant. Rachel: What?! Phoebe: When I got pregnant with the triplets, I took that test like three times just to make sure. Monica: Yes! Maybe it’s a false positive. Are you sure you peed on the stick right? Rachel: How many ways are there to do that? Phoebe: I’m-I’m just saying, don’t freak out until you’re a hundred percent sure. Rachel: All right, I’ll-I’ll take it again when I get home. Monica: You-you gotta take it now. Come on, do it as a present to me. Rachel: Okay. Thank you. Monica: Okay. Phoebe: I’ll run out and get you one. Rachel: Oh, you guys are so great. Monica: Oh, wait a minute! Who’s is the father?! Phoebe: Oh no, she won’t tell us. Monica: Oh, come on it’s my wedding! That can be my present. Rachel: Wh—Hey, I just gave you peeing on a stick. Phoebe: See? This is why you register.

What does Poebe mean by this why you register?

Answer 1

Register your choice of gift from a predefined list. Phoebe is complaining about Rachel's wedding gift; something that was not on the official gift registry. To avoid receiving a lot of inappropriate or unwanted wedding gifts, couples who are about to marry often compile a registry of gift items that they need or would like to have. Each wedding guest picks an item from the registry and buys that gift. This avoids the possibility of receiving random rubbish, like Rachel's gift a pregnancy test. Why do you register your choice on the wedding list? You register to avoid the possibility of giving an inappropriate/unwanted present.