The Conserved Oligomeric Golgi (COG) complex, an evolutionary conserved octameric vesicular tether, is essential for maintaining Golgi function by ensuring accurate delivery of resident proteins to their specific locations. Mutations in human COG subunits result in severe multi-systemic diseases known as COG-Congenital Disorders of Glycosylation (COG-CDG). This review explores the current knowledge of COG complex structure, its dynamic behavior, interactions with partner proteins, and proposed models of its cellular functions. Furthermore, we will discuss the pathological implications of mutations in COG complex subunits, as observed in model organisms and human patients.