The Ashley Book of Knots is an encyclopedia of knots written and illustrated by the American sailor and artist Clifford W. Ashley. First published in 1944, it was the culmination of over 11 years of work. The book contains 3,854 numbered entries and approximately 7,000 illustrations. The entries include knot instructions, uses, and some histories, categorized by type or function. It remains one of the most important and comprehensive books on knots.