Introduction

Can this book be called a textbook? To a certain extent the answer is yes, but not exactly. It is, so to say, a schematic textbook. More precisely, what is presented is a summary of my experience after reading textbooks, monographs and basic papers as well as working in mathematics. The key word is in the second part of the title:“a path”. This means that the main objective of these notes is very modest: to present a collection of basic, well-known and some lesser-known results that may serve as a background for future research in certain topics of harmonic analysis on the real line.