Java Card applications are called applets . Multiple applets can reside on one card. They have limited memory resources and computing power. This process of writing the permanent components into the non-mutable memory of a chip for carrying out incoming commands is called masking . Before it lands in your wallet, a Java Card needs to go through initialization and personalization.
Initialization refers to loading general data into a card's non-volatile memory.
The next step, personalization, involves assigning a card to a person. It can occur through physical personalization or through electronic personalization. Physical personalization refers to embossing or laser engraving your name and card number on the plastic surface of a card. Electronic personalization refers to loading personal data into a card's non-volatile memory, for example, your personal key, name, and pin number. Initialization and Personalization vary from vendor to vendor and issuer to issuer.