"Higher Order Fourier Analysis" by Terence Tao provides an introduction to the field of higher-order Fourier analysis, which extends classical Fourier analysis to study functions using higher-degree phase functions. The book focuses on foundational material and illustrative examples, serving as a companion to more advanced literature on the subject. It explores how these higher-order techniques are applied to problems involving arithmetic progressions and other areas where quadratic or higher-degree phases are relevant.