Crowd Sourcing is a
Community based way of working for tackling difficult or complex problems. It splits the problem into pieces, distributes the pieces to a large number of individuals (and/or computers) which complete the pieces. The completed pieces are returned to a central system and then pieces are combined to formulate the overall solution to the original problem.
Crowd Sourcing can be initiated via Contests [http://curt-rice.com/2013/01/03/science-its-your-thing-3-steps-to-a-crowdsourcing-success/].