Skin is made up of cells, which are constantly created and passing through a life cycle until finally dying and being shed at the skin surface.

A 3d model of skin cells showing three distinct layers.

The top layer of the skin, the Stratum corneum (Horny/Cornified Layer), consists of dead cells.
Below this is the Stratum granulosum (Granular Layer) in which the cell nucleii disappear.
The Stratum spinosum (Spinous Layer) with newly created cells is shown at the bottom.

Above the Stratum corneum are loose skin cells representing those that have been shed.