The 504 Words book has always been one of the greatest and main sources for learning vocabulary for language learners. This collection is suitable for people with basic knowledge of English and an understanding of fundamental concepts. The 504 collection is recommended for pre-intermediate, intermediate, and advanced learners. In fact, using this collection helps expand and strengthen the learner's knowledge. With this collection, you will learn hundreds of essential English words. The words you learn will stay with you for a long time. You will become familiar with words used by native speakers. You will also improve your English to achieve higher scores in TOEFL and IELTS exams.