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.
Parties are a wonderful way to gain 
XP and level up faster. They can also be fun if you invite real-life contacts because they will be able to check out the interior of your house.
Parties
To throw a party, tap on the 
icon in your house. Then you can tap 'throw party'.
There are two options for lengths of parties.
- mild shindig
8h - proper bender
24h
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.