The Groom's Party
The groom's party consists of the best man and the ushers. They are there to help out on the day and support the groom. The best man is usually 'in charge' of the groom's party. It is a good idea for the groom to choose just one best man and then have a supporting chief usher with specific duties to fulfil.
The ushers are the floor managers on the wedding day, in charge of crowd control and generally helping out. They must assist the best man with his duties and are the first faces guests will see when they arrive for the ceremony. Sometimes an usher will also fulfil the role of master of ceremonies instead of a toastmaster.