A citizen scientist is one that contributes to scientific advancement through means such as asking questions, donating to scientific research, advocating for, or participating directly in science while not being a professional scientist or researcher. 

The Green Paper for Citizen Science defines citizen science as “general public engagement in scientific research activities when citizens actively contribute to science either with their intellectual effort or surrounding knowledge or with their tools and resources. Participants provide experimental data and facilities for researchers, raise new questions, and co-create a new scientific culture.”

Citizen science has a broad definition that allows for many interpretations, but this broad definition and scope gives a multitude of individuals the capacity to participate in and shape the professional scientific landscape.