Democratizing science, where ‘non-certified’ experts feed into or lead scientific research.
Until recent years, science was distant from its publics. There is now a great deal of effort put into public engagement, but sometimes this amounts to little more than informing publics about scientific research, or, more cynically, do so to try and build public trust. Citizen Science, in its radical forms, disrupts the distinction between scientist/citizen, and pursues collaborative forms of knowledge production that are more genuine.
Citizen Science has expanded rapidly, partly helped by the development of technology which makes large datasets easier to access, add to and utilise by members of the public.
The term has sometimes been used a little cynically by scientists - offering so-called 'lay' people shallow opportunities to feed into research without altering its goals, premises or procedures, for the purpose of increasing trust in science.
More radical forms of citizen science, however, challenge this (examples here).