This document provides an introduction and publisher's foreword for the book "RSI: Logic, Signals & Time Frame Correlation" by Walter J. Baeyens. The foreword discusses how Welles Wilder developed the Relative Strength Index (RSI) indicator in the 1970s and how it has become very popular. The book aims to share Baeyens' research on using RSI more effectively, building on Wilder's original work. The introduction outlines how Baeyens initially had success trading based on popular RSI guidelines in 1987 but then lost money, motivating him to develop his own interpretation methods. It discusses how RSI quantifies relative rather than absolute market conditions and Baeyens' interest in Andrew Cardwell