identifier

Everyday

1. A name, number, label or sign that shows exactly who or what something is. tree →
2. (computing) A name given to something in a program, such as a variable or function name, so the computer can tell them apart. tree →

In the lessons

In computing lessons, identifiers are the names you give variables, like «score» or «lives»; they usually cannot have spaces or start with a number. In everyday life, a barcode, a passport number, a username or a pupil number is an identifier. In science, features of a plant can act as identifiers. Phrases: unique identifier, user identifier, a variable identifier.

Examples

• Each library book has a barcode as its identifier. tree →
• In Scratch we used «score» as the identifier for our variable. tree →
• Your username is an identifier, but your password must stay secret. tree →
• A unique identifier means no two things share it. tree →
• The spots on its back are a good identifier for this ladybird. tree →
• The program gave an error because the identifier had a space in it. tree →

Note

Countable noun. Verb: «identify»; «identifier» is the thing that identifies. A unique identifier belongs to just one thing; a name like «Sam» is not unique, but a passport number is. In programming, identifiers are case sensitive in many languages: «Score» and «score» can be different.