In this chapter we present an overview of a number of data and informa-
tion visualization systems and toolkits. We have concentrated primarily on
software that is freely available, to enable students interested in exploring
further in the ﬁeld of visualization to try out existing technology. These are
only a sampling, however; many ﬁne tools that we have not mentioned are
also available, and readers are encouraged to search for and download them.
We also mention some commercial packages with functionality that overlaps
with the systems we’ve chosen to describe. Caveat: the URLs given were
correct at the time of publication. These may have changed since then, or
some of the tools may no longer be freely distributed.