This book covers 160 of the most important irregular verbs that learners have to understand in order to be able to use their past and perfect tenses correctly. The book highlights the irregular parts of these verbs, defines their meanings and shows their correct uses. 'What You Need to Know about' is and open-ended series of ELT reference books on various aspects of English specially planned for intermediate learners who want to get to grips with English. Covering the most important topics of English, the series aims at helping foreign learners build a solid foundation for the learning of the language.