Prepositions have always caused a great deal of difficulty for most learners of English. This book explains the meanings of the most important prepositions clearly and shows how they are used. '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.