Spinodal decomposition is a phase separation process that occurs in systems where the growth is in amplitude rather than extent. It happens in the unstable region of a phase diagram, defined by the spinodal. Once a system crosses this boundary, phase separation occurs spontaneously without a nucleation step. This process results in high interconnectivity between the two phases. The Cahn-Hilliard equation describes the kinetics of spinodal decomposition. In contrast, nucleation and growth involve the formation of a nucleus followed by its growth. The key difference is that nucleation is large in extent but small in degree, while spinodal decomposition is small in extent but large in degree. Spinodal decomposition involves uphill diffusion, which requires large-scale fluctuations. Both processes can lead to fractal morphologies. Spinodal decomposition is characterized by the formation of a nucleus and the subsequent growth of the two phases. The process is described by the Cahn-Hilliard equation, which includes a fourth-order term that stabilizes the system against short-distance fluctuations. The spinodal decomposition mechanism is illustrated in figures showing the evolution of density profiles during the process. The phase diagram shows the miscibility gap and the spinodal boundary. The upper consolute temperature $ T_c $ marks the point where the two liquids are miscible in all proportions. The spinodal decomposition process is distinct from nucleation and growth, as it occurs without a nucleation step and involves spontaneous phase separation.Spinodal decomposition is a phase separation process that occurs in systems where the growth is in amplitude rather than extent. It happens in the unstable region of a phase diagram, defined by the spinodal. Once a system crosses this boundary, phase separation occurs spontaneously without a nucleation step. This process results in high interconnectivity between the two phases. The Cahn-Hilliard equation describes the kinetics of spinodal decomposition. In contrast, nucleation and growth involve the formation of a nucleus followed by its growth. The key difference is that nucleation is large in extent but small in degree, while spinodal decomposition is small in extent but large in degree. Spinodal decomposition involves uphill diffusion, which requires large-scale fluctuations. Both processes can lead to fractal morphologies. Spinodal decomposition is characterized by the formation of a nucleus and the subsequent growth of the two phases. The process is described by the Cahn-Hilliard equation, which includes a fourth-order term that stabilizes the system against short-distance fluctuations. The spinodal decomposition mechanism is illustrated in figures showing the evolution of density profiles during the process. The phase diagram shows the miscibility gap and the spinodal boundary. The upper consolute temperature $ T_c $ marks the point where the two liquids are miscible in all proportions. The spinodal decomposition process is distinct from nucleation and growth, as it occurs without a nucleation step and involves spontaneous phase separation.