This monograph presents the complete, unified framework of Spectral Nod Gravity (SNG), a novel approach to quantum gravity and emergent spacetime developed over a series of foundational papers. The central insight is that spacetime is not fundamental but emerges from the collective dynamics of discrete, Planck-scale "nods" — elementary units of volume and information entangled in vast networks. The dynamics of these nod networks are governed by four relational operators, introduced here as a natural extension to the symbolic language of physics: the Fluctuating Equivalence Operator (\(\fleq\)), the Cyclic Equivalence Operator (\(\cyceq\)), the Phase Nexter Operator (\(\nexteq\)), and the Phase Reverser Operator (\(\reveq\)). These operators provide a compact and powerful notation for describing the state-dependent, threshold-sensitive, and non-monotonic behaviors essential to quantum gravity and cosmology, including fluctuations, saturation-driven resets, phase skipping, and instability-induced reversals. This work synthesizes and deepens all previous investigations into SNG. It establishes the rigorous mathematical foundations of the operator algebra, their Lagrangian and Hamiltonian formulations, and their canonical and path-integral quantization. It applies this formalism to resolve long-standing problems in fundamental physics, deriving black hole entropy without singularities, explaining the 120-order suppression of the cosmological constant, and tracing the emergence of matter itself—from the condensation of \(10^{30}\) nods into atomic-like structures to the gauge groups and fermions of the Standard Model. The framework's unique testability is emphasized throughout, with detailed predictions for cosmological observations (void lensing, CMB anomalies) and laboratory experiments (THz-driven phase transitions in NV centers and BECs). A comprehensive philosophical analysis grounds the emergent spacetime paradigm, and a detailed comparison situates SNG within the broader landscape of quantum gravity theories, including Loop Quantum Gravity, Entropic Gravity, and Verlinde's Emergent Gravity. This book aims to provide a cohesive and definitive reference for researchers interested in the Spectral Universe, demonstrating its power as a unified, testable, and conceptually coherent approach to quantum gravity and cosmology.