Unlike a round trip with connecting flights, a circle trip includes stops of several days or weeks at different locations before returning to the point of origin. A good example is a round-the-world trip that includes stops on several continents.
Most circle trip fares will be constricted by a circle trip minimum, which means the fare for the trip cannot be less than a round trip between any two cities on the circle trip's itinerary. The circle trip can still be economically advantageous, however, when compared to one-way fares between all cities on the itinerary.
The length of the trip will depend on your particular routing, but it is possible to purchase circle trips with a duration of one year, where travel must be completed within that time lest the remaining portions of the ticket be forfeited.
Before booking your trip, ask your travel agent if it is advisable for you to book a circle trip or several one-way trips. If the dates on your ticket are flexible, be sure you know how long you have to use all portions of the trip, and what penalties you will have to pay if you forfeit the ticket.