There are three castes of bees in a hive: Queen, Drones, and Workers. In short, the Queen's purpose is to lay eggs, the Drones' purpose is to mate with a virgin queen, and the Female Workers do everything else.
Nearly all the bees in a hive are female workers, and there can be up to 40,000 in a single hive at peak production. During this peak time of production, when flowers and blooming and the nectar is flowing, the life span of a worker bee is about 6 weeks long; however, when the honey flow is over and egg/brood production stops, a worker bee can live upwards of 4 months through the winter months.
An amazing part of worker bees is how their role changes depending upon their age. Below are there various functions as they mature (source: en.wikipedia.org/wiki/Beekeeping)
Days 1-3 -- Cleaning cells and incubation
Day 3-6 -- Feeding older larvae
Day 6-10 -- Feeding younger larvae
Day 8-16 -- Receiving honey and pollen from field bees
Day 12-18 -- Wax making and cell building
Day 14-Death -- Entrance guards; nectar and pollen foraging