  In this short essay, we show how computer experiments, and especially
visualization, allowed for the investigation and discovery of phenomena which
would have passed unnoticed. We shall also highlight the importance of
interactivity between the computer and the user. We do this by surveying
several historical examples from mathematics and the physical sciences. Many
pictures, and even hyperlinks to online interactive numerical experiments, are
provided. Needless to say that we do not claim to be exhaustive, and that the
chosen examples reflect our taste as well as our limited knowledge. Hyperlinks
to several online interactive digital experiments are provided.
