Figure 1 from: Sturm U, Schade S, Ceccaroni L, Gold M, Kyba C, Claramunt B, Haklay M, Kasperowski D, Albert A, Piera J, Brier J, Kullenberg C, Luna S (2018) Defining principles for mobile apps and platforms development in citizen science. Research Ideas and Outcomes 4: e23394. https://doi.org/10.3897/rio.4.e23394

Figure 1 Definitions in order to establish a common understanding for app, webpage, platform and portal and considering that the boundaries are not always clear and in some cases tools might act as a portal and a platform at the same time.