Pigmentation is the colouring of your skin. It is a skin condition where patches of the skin turn into a darker shade of colour due to excessive presence of melanin, found on skin surface.
Melanin is produced by melanocytes and functions as miniature umbrellas to skin cells to protect the skin from sun and UV damages. Pigmentation is due to the deposition of the pigment melanin, which is produced by specialized cells called melanocytes. Other pigment-related terms include hyperpigmentation (too much pigment), hypopigmentation and underpigmentation (too little pigment), and depigmentation (loss of pigment).