Errors in writing and speaking any language could create difficulties for the users of that language. Even the most seasoned and established writers are likely to commit some errors and they might not be aware of those errors. In order to write good and perfect English, a good understanding of grammar, sentence formation and thoughts is a must. This book is a guide on very common mistakes frequently committed in the course of writing and speaking English language, both at personal and professional level. Special attention has been paid to the spelling mistakes for they constitute a major part of the mistakes committed by the modern users of English. A special attraction of the book is that it offers practice exercises along with their answers which will enable the readers to check their understanding of the English language. Besides, there are many solved and unsolved exercises as well for further practice. This book is highly useful for students and professionals alike. It is a must read for all those who are interested in speaking and writing good and perfect English.