An circular intersection, known in other parts of the world as a roundabout or traffic circle. By far the best form of intersection, as traffic is seldom required to stop, however the advantages of rotaries are often negated by drivers who are too stupid to properly navigate them.
There are a few rules to rotaries.
#1. Traffic already inside the rotary has right of way.
#2. The outside lane is for taking the first or second exits only. You may not go all the way around the rotary in the outside lane.
#3. The inside lane may be used for going beyond the first two exits.
#4. Once inside the rotary, do not stop. Rotaries are designed so that traffic inside the rotary does not have to stop, if you stop, drivers behind you will not be expecting it, causing the risk of a rear-end collision. If you cannot get to your exit, simply drive around the rotary again.
Ever since they installed that new rotary, traffic has moved much more smoothly.
Some dumbass in an SUV talking on a cell nearly sideswiped me when he/she couldn't stay in his/her own lane in the rotary!