This monograph is both a summary of data and a methodological guide to ribosomes - these essential components of a living cell, The book contains all the modern data on the chemical and physical properties of ribosomes, terminology has been clarified, methods for isolation and purification of ribosomes from various sources are given, structure and composition of ribosomes of various origin, their role in protein biosynthesis and many other theoretical and methodological issues are considered. Designed for biochemists, biophysicists, histologists, cytologists, microbiologists, geneticists, virologists, as well as chemists and physicists working in the field of molecular biology.