The horny outer layer of the epidermis, consisting mainly of dead or peeling cells. Abbreviated SC, it resides directly above the stratum germinativum (SG). The skin's junkyard, this is where old skin goes to die. You will also have a thriving bacterial population feeding off of the dead skin cells, no matter how much you wash. This is not a bad thing, as most bacteria do us no harm.
Your SC will generally replace itself every two weeks, as cells flake off. Your SC contains a lot of keratin, which helps your skin stay hydrated. It does this in part by absorbing water, and in part by preventing evaporation. When your fingers wrinkle from being in the water too long, this is because the keratin in your SC is swollen from absorbing too much water; as the keratin expands it causes the SC to 'buckle', and being firmly attached to the epidermis, it cause your skin to stretch out of shape with it.
The SC is thickest on your hands and feet, because these are the areas that get the most wear and tear, and thus need the most protection.