This book constitutes the refereed proceedings of the 6th Annual International Conference on Computing and Combinatorics, COCOON 2000, held in Sydney, Australia in July 2000. The 44 revised full papers presented together with two invited contributions were carefully reviewed and selected from a total of 81 submissions. The book offers topical sections on computational geometry; graph drawing; graph theory and algorithms; complexity, discrete mathematics, and number theory; online algorithms; parallel and distributed computing; combinatorial optimization; data structures and computational biology; learning and cryptography; and automata and quantum computing.