  The aim of visualization is to support people in dealing with large and
complex information structures, to make these structures more comprehensible,
facilitate exploration, and enable knowledge discovery. However, users often
have problems reading and interpreting data from visualizations, in particular
when they experience them for the first time. A lack of visualization literacy,
i.e., knowledge in terms of domain, data, visual encoding, interaction, and
also analytical methods can be observed. To support users in learning how to
use new digital technologies, the concept of onboarding has been successfully
applied in other domains. However, it has not received much attention from the
visualization community so far. This chapter aims to fill this gap by defining
the concept and systematically laying out the design space of onboarding in the
context of visualization as a descriptive design space. On this basis, we
present a survey of approaches from the academic community as well as from
commercial products, especially surveying educational theories that inform the
onboarding strategies. Additionally, we derived design considerations based on
previous publications and present some guidelines for the design of
visualization onboarding concepts.
