"Word Power Made Easy" by Norman Lewis, a well-known book for building English vocabulary.

Purpose:
It's designed as a comprehensive handbook to improve vocabulary and mastery of the English language.

Methodology:
The book focuses on teaching word roots and etymology, rather than rote memorization, to help users understand how words are formed and used.

Target Audience:
It's widely used by individuals looking to enhance their general vocabulary and by those preparing for various language proficiency and competitive exams like TOEFL, IELTS, SAT, GRE, SSC CGL, and CLAT.

Features:
It includes exercises, tests, and a focus on understanding word origins to help readers build a superior vocabulary and improve reading, writing, and speaking skills.