Snakes keep growing, so they shed their skin periodically (from time to time).
The process of shedding skin is called ecdysis.
Before shedding their skin, snakes look a bit bluish and their eyes become cloudy with a white or blue appearance. This is caused by fluid or liquid between the layers of the skin, called mucous.
The skin becomes loose at the lips and sheds off when snakes rub against things.

snake skin
Ecdysis is normal shedding of the skin when snakes grow. Most snakes shed their skin once a year, but some snakes that are growing quickly, like young ones, shed their skin about every two months.
Abnormal (not normal) shedding of the skin can occur if they have mites, malnutrition (not enough to eat), trauma (shock), or other reasons.
Abnormal shedding of the skin is called dysecdysis.
Amphibians (frogs and toads) usually eat their shedded skin, but snakes don’t.

snake skin
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM