This work is a tribute to the life and work of Guido Weiss, a mathematician whose profound contributions shaped the field of harmonic analysis over a span of more than six decades. His groundbreaking research, from pioneering real and complex analysis to his later work on wavelets, continues to influence generations of scholars. More than just a researcher, Guido was a mentor, collaborator, and friend to many, creating a global community of mathematicians. His charisma and generosity fostered lasting professional and personal connections across continents, touching lives far beyond academia. This volume features contributions of collaborators, students, and colleagues of Guido, who had a particularly intense relationship with him. From a heartfelt remembrance of Guido Weiss to advanced discussions on spectral synthesis and wavelet theory, this collection contains a diverse landscape of mathematical results. Readers will delve into topics such as the compactness of bilinear commutators, the intricacies of analytic families in extrapolation theory, and the intersections of time-frequency analysis with modern learning techniques. With contributions to Hardy spaces, Haar multipliers, and crystalline measures, this book serves both as a tribute to past achievements and a beacon for future exploration.