Citizen science has grown significantly due to societal and technological trends. Increased education levels, leisure time, and sharing economies have empowered more people to engage in scientific work. Advances like broadband internet, mobile devices, and DIY electronics have also facilitated participation. Current citizen science involves collaborative problem definition and data collection between citizens and scientists. Government agencies and policies are increasingly recognizing the value of citizen science data. Further development is still needed regarding sustainable funding models, data standards, and expanding citizen science to new domains.