Abstract Formal Concept Analysis and Contextual Logic are related mathematical theories about concept hierarchies and concept graphs, respectively, which have been developed to support humans in their thought and knowledge. The aim of this article is to give an introduction to the main themes such as “The Mathematics of Formal Concept Analysis”, “Applications of Formal Concept Analysis”, “Contextual Concept Logic”, and Contextual Judgment Logic”. The presentation of the themes begins with a short desription abbout “The Birth of Formal Concept Analysis.”