Crowdsourcing involves outsourcing tasks to a large, undefined group of people via the internet. It has existed for years in various forms like software testing but the term was coined in 2006. Common types of crowdsourcing include crowdfunding, crowdsourced designs, and crowdwisdom. The pros are that it provides a large, diverse pool of talent and knowledge at low cost. However, managing large crowds and ensuring quality can be challenges. Popular crowdsourcing sites include Freelancer, 99designs, and InnoCentive for various tasks like design, testing, and problem-solving.