Parties are exactly what they are called: a party! If you own a house outside of the Neighborhood Apartment, you can host parties. You can invite anyone on your contacts list. If you invite in-game contacts, they will definitely arrive. If you invite any Game Center or Facebook contact to a party, the actual person must play and respond to your invitation in their own game.
There are two options for lengths of parties.
After you start your party, you will see more of the icons around your house. Tap on them to invite people. You can invite up to 6 people to your parties.
The parties act like filming in a studio. They have a rating, actions, and a reputation. Starnews reports your parties by how awesome your party was. Getting high ratings can also net you fans!
You may also leave your house at any time during your party to do another quest or get energy without threatening your party.