How do you define and use interfaces in TypeScript?

Interfaces define the structure of objects and provide contracts for classes. Basic Interface: interface User { id: number; name: string; email?: string; // Optional property readonly createdAt: Date; // Read-only property } const user: User = { id: 1, name: "John Doe", createdAt: new Date() }; Interface Features: • Optional Properties: Use `?` for optional fields • Readonly Properties: Use `readonly` to prevent modification • Method Signatures: Define function types interface Calculator { add(a: number, b: number): number; subtract(a: number, b: number): number; } class BasicCalculator implements Calculator { add(a: number, b: number): number { return a + b; } subtract(a: number, b: number): number { return a - b; } } Interface Extension: interface Animal { name: string; } interface Dog extends Animal { breed: string; }