Citizen science projects can be categorized in different ways based on levels of public participation and types of scientific tasks involved. Some key typologies include contributory vs collaborative vs co-created projects, and projects involving data collection, processing, and transcription tasks. The level of public participation and task complexity determine scalability, technology requirements, volunteer management needs, and implications for project design such as evaluating resources and goals, recognizing tradeoffs, and addressing constraints to determine the appropriate design.