The book "Principles of Language Learning" by Harold Palmer is a classic study in the field of linguistics and methods of learning foreign languages. In this work, the author considers the main principles and methods of language learning, paying attention to the qualitative and quantitative aspects of the language acquisition process. Palmer examines the influence of various factors on the success of language learning, separates important aspects from minor ones and provides clear recommendations for optimal approaches to language learning. This book is an important resource for anyone interested in the methodology of language learning and who wants to understand the processes that occur in the human brain during language learning.