Table 1.

Different typologies of citizen science and citizen science-related activities.

Terminology used	Orientation and focus	Classifications within typology
Citizen Science	Multi-dimensional focus on types of the activity	Action-oriented, conservation, investigation, virtual and education [12]
	Knowledge producer and activity/project goal and focus	Matrix approach: Citizens or researchers as main knowledge producers, addressing a research question or intervention in a socio-ecological system [13] based on [12,14]
	Nature of the participatory task	Passive sensing, volunteer computing, volunteer thinking, environmental and ecological observations, participatory sensing and civic/community science [15,16]
	Learning dimensions	Learning of project mechanics, pattern recognition skills, on-topic extra learning, scientific literacy, off-topic knowledge and skills and personal development [17]
	Complexity of the citizen science approach and participation structure	Matrix approach: Elaborate approach vs. simple approach, and mass participation vs. systematic monitoring, and in addition computer-based projects [18]
	Communication goals of a citizen science project	Goals of communication messages from citizen science projects: Awareness, Conversion, Recruitment, Engagement, Retention [19])
	Education aspects	Increasing interest in science, using scientific tools, specific disciplinary content, scientific reasoning, to developing an identity in science and more [20]
	Multi-dimensional focus on the nodes of engagement	Behavioural activities, affective/feeling, learning/cognition and social/project connections [21]
	Activity type and epistemic practice	Sensing, computing, analyzing, self-reporting, making [22]
Public Participation in Scientific Research (PPSR)	Relational aspects and role definitions, with implicit information on depth of involvement	Consulting, contributory, collaborative, co-created, and collegial [14] which is an expansion of [11]
Citizen Engagement in Social Innovation	Direction/goal of a project and scale (based on number of participants)	Matrix typology: Investigating present states to developing future solutions; from few to many participants [23]
Citizen Science and Volunteered Geographic Information	Engagement of participants in an activity	Crowdsourcing, distributed intelligence, participatory science and extreme citizen science [24]
Citizen science and environmental management	Relationship type and type of activity encounter	Matrix approach: Cooperative vs. adversarial relationships and deliberate vs. serendipitous [25]
Citizen Science and Conservation	Type of projects/ formats of citizen science	Bioblitzes, ongoing monitoring programmes, bounded field research and inventory projects, data processing projects [26]
Citizen Observatories	Multi-dimensional for a systematic review framework	Geographic scope, type of participants, establishment mechanism, revenue stream, communication paradigm, effort required, support offered, data accessibility, availability and quality [27]
Citizen Science and Innovation Management	Business model of the project and its funding	Motivated individual; Small Crowdsourcing; Outreach; Research and Innovation (R&I); and Long Term NGO [28]
Citizen Science in Health and Biomedical Research	Research focus and modes of participation	Observational and Interventional research; matrix approach to participation models: Professional driven vs. Public driven and Independent participation vs. Collective participation, resulting in Traditional science, N-of-1/DIY science, N-of-many-1’s/contributory and N-of-we/co-created participation modes [29]
Community Based Monitoring	Multi-dimensional on the aspects that can influence the establishment and functioning of a CBM	Goals and objectives of the project, technologies, participation, power dynamics [30]
Policy and Citizen Science	Policy outcomes and impact	Policy outcomes—from addressing a local environmental nuisance, to monitoring national policy and the stages of the policy cycle: issue identification, measure identification, implementation, monitoring (effectiveness) [31]