This introduction to English grammar is aimed equally at those who are taking first steps in learning English and at native speakers or who are trying to improve a basic grasp of the grammatical rules that underpin the English language. It is grammar that gives any language its character and its practical usefulness, and an understanding of grammatical rules and conventions is as important as mastery of the vocabulary to achieve any degree of fluency. English has a complex grammar and it is sometimes difficult to know which form of words to use. Sometimes the rules are logical and predictable, but on many occasions words do not behave as they might be expected to. Furthermore, often the speaker or writer must choose between two equally acceptable alternatives, the correct use of which depends entirely upon the context or the degree of formality involved. What may be acceptable in everyday conversation, for instance, may not be so acceptable when written down. Knowing how to choose the best option is where a guide like this one can prove indispensable. The text of this book is subdivided into sections comprising several units, each of which tackles a potentially problematic aspect of English grammar. Care has been taken in each unit to explain the topic in simple terms and with numerous examples illustrating how the rules of grammar are applied in real life. Where useful, additional information is added in boxes under the heading Grammar Extra. Cross-references guide the reader to relevant information elsewhere in the text.