What does "colon" mean in programming?

colon is one of the most common terms in software development. This guide explains what it means, how it is used in practice, and why it matters, with real examples from the developer world.

Definition

The : character. In Python and Ruby it ends block headers (if x:). In TypeScript it separates a variable name from its type annotation (name: string). In JSON and object literals it separates keys from values.

Example

"const age: number = 30; // colon introduces the type annotation"

Related terms

semicolon
type annotation

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