What is TypeScript and how does it differ from JavaScript?

TypeScript is a statically typed superset of JavaScript developed by Microsoft. Key differences: 1) Static typing - TypeScript adds optional static type checking, 2) Compile-time error detection - catches errors before runtime, 3) Better IDE support - enhanced IntelliSense and refactoring, 4) Modern JavaScript features - supports latest ECMAScript features, 5) Compilation - TypeScript compiles to plain JavaScript.