TypeScript is an open-source, statically typed superset of JavaScript developed by Microsoft, designed to enhance JavaScript applications for both client-side and server-side execution by introducing type checking and error prevention features. It allows developers to define variable types, utilize type inference, and leverage tuples, enums, and the `any` type for flexible coding, while also supporting traditional JavaScript data types like arrays, strings, numbers, booleans, null, and undefined. TypeScript's capability to prevent runtime errors and facilitate IDE functionality makes it appealing for developers with a background in typed languages. Additionally, it supports advanced type applications such as declaration files and function type definitions, contributing to more reliable and maintainable codebases.