A system used by airlines for reducing their costs and (apparently) increasing traveller headache
The primary idea behind the hub and spoke system is to provide flights to all of the minor airports from only one or two major airports, thereby eliminating most direct flights between the minor airports and reducing the number of flights required for the airline to service all of its airports.
The system is so named because if you draw lines on a map illustrating all of the resulting flights, one finds that the picture looks rather like the hub and spokes of one or more wheels.
The bad news for travellers is that the hub and spoke system tends to eliminate a lot of non-stop flights. If the airline you are flying with uses a hub and spoke system (almost all do these days), unless you are traveling between two major cities chances are you will be flown from your starting location, to the hub, switch planes, and then be flown on to your destination. If your source and destination are both minor airports, especially minor airports located across the country from each other, chances are you'll be flown from your starting airport to one hub, switch planes, fly to a second hub, switch planes, and finally fly to your destination.
If there is a good aspect to the hub and spoke system from the traveller's point of view, its that one almost never has to stop more than twice to get where you're going.