In this self-contained monograph, finite generalized quadrangles are
classified by symmetry, generalizing the celebrated Lenz--Barlotti
classification for projective planes. It serves as an introduction to
the combinatorial, geometrical, and group-theoretical concepts that
arise in the classification and the general theory of finite generalized
quadrangles. Several long-standing open problems are solved by using a
mixture of geometrical, combinatorial, and group-theoretical arguments.
Further, a conjectural classification program for all finite transaltion
generalized quadrangles is decribed. The book will be useful to advanced
graduate students and researchers in geometry, group theory, or
algebraic combinatorics.