Triathlon races are made or lost during transition times. I suppose racing in the morning to get showered, dressed and hair brushed before the kids wake up doesn't come close to comparing the speed in which this is needed during a triathlon.
There are two transitions in a triathlon; T1 is the transition between the first and second leg, and T2 is the transition between the second and third leg. Both times are counted in the overall race time, so if you waste a minute or two here, its equivalent to running an entire minute slower per mile. In other words, take your transitions seriously. Every second between the start of the first leg and the end when you cross the finish line counts. Therefore, smooth and quick transitions are key.
A great reference document is here.