Explore a comprehensive lecture on active processes in cells and tissues, focusing on phase separation in active systems. Delve into the physics of cellular compartments, droplet formation, and granule dynamics. Examine the thermodynamics of phase coexistence, protein gradients driving granule segregation, and the behavior of chemically active droplets. Investigate centrosome dynamics, RNA-protein assemblies, and the potential of active droplets as models for photocells. Gain insights into growth-division cycles and the organization of chemistry in space within living systems. This lecture, part of the ICTP-ICTS Winter School on Quantitative Systems Biology, offers a deep dive into the complex and dynamic nature of living matter, exploring how spatial patterns and morphologies emerge at cellular and multicellular scales.