The monograph aims at a general outline of old and new results on representations of finite-dimensional algebras. In a theory which developed rapidly during the last two decades, the lack of textbooks is the main impediment for novices. Therefore special attention is paid to the foundations, and proofs are included for statements which are elementary, serve comprehension or are scarcely available. In this manner the authors try to lead the reader up to a point where he can find his way through the original literature. The discourse is centered around the fairly complete theory of finitely-represented posets and algebras. The monograph provides many examples and all the needed background on decomposition theorems, quivers, almost split sequences and derived categories. It includes a survey on representations of tame and wild quivers, lists of critical algebras and a proof of the old conjectures of Brauer and Thrall.