ID is an acronym that stands for four different terms: NAME, EGO, CARD, and USER. NAME is a four letter word that is used to identify a person or thing. EGO is a three letter word that refers to a person's sense of self-importance or self-esteem. CARD is a four letter word that is used to identify a person or thing through a physical CARD or digital code. USER is a four letter word that refers to someone who uses a product or service. EST is a three letter word that stands for Eastern Standard Time, which is the time zone in the eastern part of North America.