TypeScript is a programming language that extends JavaScript with a static type system. It helps developers describe the types of values used in their code, such as strings, numbers, and objects. By checking these types before execution, TypeScript can identify many mistakes during development.

One of TypeScript’s main benefits is clearer code. Types and interfaces describe the structure of data and the inputs and outputs of functions. This makes code easier to understand, improves editor suggestions, and helps teams make changes confidently as applications grow.

TypeScript supports features such as union types, generics, and type inference. Union types allow a value to have more than one possible type, while generics help developers create reusable functions and components that preserve type information. Type inference reduces the need to write explicit annotations when a type can be determined automatically.

TypeScript code is converted into JavaScript so it can run in browsers and environments such as Node.js. It works with tools including React, Next.js, and Express. Although it improves development-time checks, it does not automatically validate incoming data at runtime, so applications still need validation for external inputs.