The use of clickers (also referred to as Audience Paced Feedback, Classroom Communication Systems, Personal Response Systems, Electronic Voting Systems, Student Response Systems, Audience Response Systems, voting-machines, and zappers) has grown in college chemistry classrooms within the last decade. This review summarizes the pedagogic applications of research on clickers as well as insights from their practical use. Fifty-six publications reporting on the use of clickers in college-level science classrooms are categorized as practical application or research studies, and reviewed. Publications on the practical use of clickers suggest that students have a positive attitude towards the technology and that many benefits and few drawbacks are associated with its use. Research studies show that the use of clickers results in measurable increases in student learning in some cases and inconclusive results in other cases. In every published report of student improvement with the use of clickers, the course included student collaboration of some form.