There are now at least as many typologies and categorisations of citizen science as there are ideas and explanations of what citizen science is. What counts as citizen science is not a foregone conclusion. In the Horizon 2020 project CS Track, the authors systematically examined different approaches to categorising citizen science activities and created a grid of citizen science activities and their dimensions, the Activities & Dimensions Grid of Citizen Science. The Grid is based on the European Commission's broad concept of citizen science. More detailed and systematic than previous categorisations, it shows the complexity and contexts of citizen science, namely what can be citizen science and on which dimensions such as the location of participation, the requirements for participating in a citizen science activity, demographic aspects of who is participating, funding schemes and others, citizen science activities depend. The systematic consideration, the result of which is the Grid, allows a better view of possible pitfalls and ethical questions, as well as questions of inclusion and exclusion in citizen science. Some of them only become visible through this, others only become sufficiently specific and thus accessible for an answer. This paper presents the above-mentioned grid, how the partly quite different categorisations of citizen science were incorporated and how it can be used for citizen science activities to identify possible pitfalls, ethical aspects as well as aspects of inclusion and exclusion of the respective citizen science activities.