A wonderful book to get started with and deeply inside of FCA, introducing important basic and advanced notions and results. It contains * the elementary ideas and motivation of FCA as invented by Rudolf Wille (see the reprint of his original paper: [[bibtex/20076ddf2562946e870f89834b6d1cd25]]), * several fundamental algorithms, * a great deal of algebraic theory bridging the gap between FCA and complete lattice theory and * several advanced notions, decompositions and constructions of concept lattices.