The book "Work on Your Vocabulary - C1" by HarperCollins is a comprehensive textbook specifically designed for learners of the English language at an advanced level (CEF C1). It offers a structured approach to the vocabulary necessary for achieving a high level of language proficiency. In a total of 30 units, various topics are covered, supported by clear explanations and examples. Each unit includes practical exercises that help learners internalize what they have learned and apply it confidently in both written and spoken communication. The content is based on extensive research and the expertise of language professionals, ensuring that the words and phrases addressed are relevant and up-to-date. The book is suitable for both self-study and classroom use, making it a valuable resource for students and teachers alike.