Galaxies are found in groups and clusters, and these are only the

start of a hierarchy of cosmic structures up to the largest scales

observed. This lecture introduces the properties of groups and

clusters of galaxies, superclusters (clusters of clusters), and

large scale structure with filaments of superclusters surrouning

vast voids. We start with our Local Group, and then expand our

view to encompass the depths of intergalactic space.

Recorded 2006 February 14 in 1008 Evans Laboratory on the Columbus campus

of The Ohio State University.