I've agreed to buy a domain previously owned, now what?

I wanted to buy some domain already owned by someone else. So I contact it's registrar, negotiated the price and came to a deal. Everything was done via e-mail.

Now what? How the actual domain ownership is transfered to me? What information should I asked for before giving any money to the registrant?

Note: the registrar is a well known domain name registrar, accredited by the ICANN and everything.

From serverfault Toto

• you need to get authinfo to get move that domain from one registrar [ of seller ] to your registrar. it's a string of text, you give it to your registrar - they'll know what to do with it.

  From pQd