Frontend development has undergone a major transformation with modern frontend technologies, such as React, Angular, Vue, and so forth. This is largely due to the wide adoption of component-based architecture provided by these wildly successful technologies. This book aims to not only guide readers from the foundational building blocks of creating well structured interfaces but also provide an exhaustive list of different philosophies for creating modular, extendable and scalable U&I --- i.e. UI intended for all developers, like you and I.