This monograph studies the geometry of a Kummer surface in ${\mathbb P}^3_k$ and of its minimal desingularization, which is a K3 surface (here $k$ is an algebraically closed field of characteristic different from 2). This Kummer surface is a quartic surface with sixteen nodes as its only singularities. These nodes give rise to a configuration of sixteen points and sixteen planes in ${\mathbb P}^3$ such that each plane contains exactly six points and each point belongs to exactly six planes (this is called a ``(16,6) configuration''). A Kummer surface is uniquely determined by its set of nodes. Gonzalez-Dorrego classifies (16,6) configurations and studies their manifold symmetries and the underlying questions about finite subgroups of $PGL_4(k)$. She uses this information to give a complete classification of Kummer surfaces with explicit equations and explicit descriptions of their singularities. In addition, the beautiful connections to the theory of K3 surfaces and abelian varieties are studied.