 Citizen Science is a rapidly growing field that involves people's participation in data collection, analysis, and decision-making. It has been defined as a form of public participation in scientific research and a collaborative effort between professional scientists and volunteer citizens. The terms used to describe citizen science vary widely, including public participation in scientific research, civic science, volunteer geographic information, community-based monitoring, participatory environmental monitoring, citizen observatories, citizen science initiatives, citizen science projects, and citizen science programs. These terms have different implications and connotations which can lead to confusion when trying to understand the scope of citizen science. To address this issue we propose a set of terms that could be used to better define citizen science and its participants. This article was authored by M. V. Itzel, Jessica L. Cappadonna, Chris Santos-Lang, and others.