Paul Erdös, who has been called the world's greatest problem poser and solver, has published more papers than any mathematician alive. The aim of this selection from his vast output is to bring together his most important papers. Over 80 contributions are included, which are grouped into four parts and sixteen chapters as follows: Papers of Special Interest: an early gem—problems; Graph Theory: representation of graphs—coloring of graphs—extremal graph theory—circuits—assorted graph theory; Combinatorial Analysis; Ramsey's theorem—property B—systems of sets—block designs—tournaments—information theory; Miscellany: random objects—Latin squares—geometry. Erdös is a kind of mathematical wandering scholar. Over the past 40 years, he has traveled to more than 200 universities throughout the world, posing problems and giving lectures: "I have no permanent position or address."