Phosphatidylinositol kinases catalyze the phosphorylation of phosphatidylinositol or its phosphorylated derivatives at positions 3, 4 or 5 of the inositol ring. These hydroxyl groups can be phosphorylated individually and in combinations. As a consequence, seven different phosphoinositides can be generated: three monophosphates (PI3P, PI4P and PI5P), three bisphosphates (PI(4,5)P[[2]], PI(3,4)P[[2]] and PI(3,5)P[[2]]) and one trisphosphate PI(3,4,5)P[[3]]. These phosphoinositides can act as signalling molecules to mediate/regulate a range of cellular and physiological processes, including cell polarity, cell migration, autophagy, growth, development, and ageing. (Adapted from FBrf0227909.)