Citizen science is research conducted with participation from the general public, or amateur/nonprofessional researchers or participants for science, social science and many other disciplines. There are variations in the exact definition of citizen science, with different individuals and organizations having their own specific interpretations of what citizen science encompasses. Citizen science is used in a wide range of areas of study including ecology, biology and conservation, health and medical research, astronomy, media and communications and information science.

Zooniverse is a citizen science web portal owned and operated by the Citizen Science Alliance. It is home to some of the Internet's largest, most popular and most successful citizen science projects. The organization grew from the original Galaxy Zoo project and now hosts dozens of projects which allow volunteers to participate in crowdsourced scientific research. It has headquarters at Oxford University and the Adler Planetarium. Unlike many early internet-based citizen science projects which used spare computer processing power to analyse data, known as volunteer computing, Zooniverse projects require the active participation of human volunteers to complete research tasks. Projects have been drawn from disciplines including astronomy, ecology, cell biology, humanities, and climate science.