The term "coopetition" refers to a system in which various business firms that are, at times, competitors can work together when it is to their mutual benefit to do so. Coopetition is based on the idea that business does not always need to be a zero-sum game.
One good way to engage in coopetition is to collaborate with your competitors to enlarge the overall size of the market for your products. Think, for example, about tablet computers. If all the firms that are trying to sell tablet computers work together to market the tablet computer in general as something people need, many more people will want to buy tablet computers. This will benefit all the firms in the industry.
By doing things like this, firms that compete with one another can sometimes act in ways that are mutually beneficial. This is coopetition.