Practical English Usage is a reference book written by Michael Swan that focuses on common problems in English grammar and usage. It provides clear explanations and examples to help learners understand the complexities of the English language. The book covers a wide range of topics, making it a valuable resource for both students and teachers. The book is organized into sections that address specific issues, such as verb forms, prepositions, and articles. Each entry is concise and easy to navigate, allowing users to quickly find the information they need. Overall, Practical English Usage serves as an essential guide for improving English language skills.