Greying hair can be classified into two main types:

Natural Greying: This type of greying occurs as part of the ageing process and is influenced by genetic factors. It typically starts around middle age and progresses gradually over time.

Premature Greying: Premature greying refers to the onset of grey hair before age 20 in Caucasians, before 25 in Asians, and before 30 in Africans. Genetic predisposition, environmental factors, or underlying health conditions can cause it.

For More Details:

https://www.vcaretrichology.com/grey-hair-treatment-in-chennai.php