Buying a home does not occur in a vacuum, involving only you and the seller. There are all kinds of people and services involved behind the scenes to make it happen. Since some of these services affect both you and the seller, there will have to be an agreement on which companies you will use for them.
As a buyer, you should request the title insurance company, closing/settlement company and who will hold the escrow deposit(s) when you make the offer. If you are unfamiliar with these service providers, your Realtor can provide a list of recommendations from which you can choose.