PIN is a code that a person has to be enter when they want to complete a transaction using some card.
This is a unique number which only the user of the card would know.
This makes it a layer of safety for the card as any unknown person would not be able use the card.
This PIN is anything from a 4 to 6 digit code that a person has to remember.
A person can change their PIN when they want to maintain the security of their cards.