SIM ( Subscriber Identity Module or Subscriber Identification Module) is an integrated circuit which intended to securely store the international mobile subscriber identity (IMSI) number and its related key. Physical SIM card is known as a Universal Integrated Circuit Card (UICC) and made of PVC (Polyvinyl Chloride).
A SIM card contains International Mobile Subscriber Identity (IMSI) number which helps to identify the user of mobile. Basically SIM used to mobile telephone. For user access it has two type passwords, Personal Identification Number (PIN) and Personal Unblocking Key (PUK). Their PIN is for ordinary use and PUK used to unblock PIN. Many SIM has storage to save contact information.
On the field of physical SIM card eSIM is an era. eSIM replacing physical SIM card. It used a software-based system which is unremovable.