This is a practical reference book for learners and teachers of English as a second or foreign language. Its main purpose is to provide intermediate and advanced learners with easy access to the information they need in order to correct their errors, both in system grammar and in word grammar. Special features include comprehensive coverage of all the major errors, an alphabetical arrangement combined with extensive cross-referencing for easy access, and a method of presentation that provides opportunities for active learning. Each entry shows a Common error side by side with its correction, followed by a clear simple explanation. This enables learners to identify the error, see and understand the corrected form and, as a result, improve both their spoken and written English.