Buyers and sellers have to deposit documents and money with a neutral third party to be held. When certain conditions agreed upon by both buyer and seller are met, the third party (the "escrow holder") then distributes the documents and the money. So after your offer has been accepted, you and the seller must agree on an escrow or settlement company to act as an independent third and ensure that each party receives what is due to them. Since this is a very important task to both you and the seller, you must both agree to the company and the fees they charge.