The presently applicable Rules explained in this book were adopted by the International Maritime Organization (IMO) in the ‘Convention on the International Regulations for Preventing Collisions at Sea’ on 20th October 1972 which entered into force on 15th July 1977. They have been amended several times since then; in 1981, 1987, 1989, 1993, 2001, 2007 and the last in 2013 by resolution A.1085 which became effective from 1st January 2016 and adds Part ‘F’ to the Rules. There were earlier versions of these Rules too; the historical details about their evolution is a separate matter.