Clathrin-coated endocytic vesicles are produced by a complex modular protein machinery that transiently assembles on the plasma membrane. This machinery selects and concentrates cargo molecules and shapes the membrane into a vesicle.Forces arising within the membrane during deformation counteract forces generated by the endocytic protein modules. Physical parameters such as membrane tension and rigidity control the dynamics of clathrin-mediated endocytosis.Many endocytic proteins bind phosphoinositides, which are critical for organizing the sequence of protein assembly throughout endocytosis.The endocytic machinery is evolutionarily ancient and highly conserved, but it has adapted to varying force requirements in different lineages.