This book is a general introduction to Higher AlgebraicK-groups of rings and algebraic varieties, which were firstdefined by Quillen at the beginning of the 70's.These K-groups happen to be useful in many different fields,including topology, algebraic geometry, algebra and numbertheory.The goal of this volume is to provide graduate students,teachers and researchers with basic definitions, conceptsand results, and to give a sampling of current directions ofresearch.Written by five specialists of different parts of thesubject, each set of lectures reflects the particularperspective ofits author. As such, this volume can serve asa primer (if not as a technical basic textbook) formathematicians from many different fields of interest.