All listing agreements lay out the ground rules for how your broker will sell your home for you. They also all share certain common characteristics, including how long the listing will last. They set the price you want for your home as well as the commission you'll pay the broker for successfully selling it. Lastly, most listings have a set of exclusions under which you'll owe no commission whatsoever. Get everything in writing before signing.
The exclusive right to sell listing is the most common type used in the business. In it, the broker gets paid the commission you've negotiated with her no matter who sells your home. For example, if another broker finds a buyer for your home, part of your broker's commission is split with the other broker. You'll also usually owe a commission even if you're the one who found the buyer.
The next most common form of real estate listing is the exclusive agency version. Though your broker will still represent you, you retain the right to sell your home on your own and not pay a commission. This listing works especially well for those instances when you've found just such a buyer. In that case, no broker commission is paid out by you. Should your broker find a buyer, though, you'd owe him his rightful commission.
Open listing agreements are the most wide-open of all the listing types. It's nonexclusive and it gives you the right to sell your home on your own. You can have such a listing with as many brokers as you'd like. You only pay a commission if a broker with whom you have such an agreement brings you a buyer. Typically, commissions paid under open listings are about half that of the other listing types.
Within the law, almost everything about a real estate listing can be negotiated. Commissions, as well, are almost always a negotiable item. And commissions are usually highest in exclusive right to sell listings. That's because brokers often invest a great deal of resources when selling a home under such an agreement. Most sellers usually still try to have a commission exception created should they sell the home on their own, though.