Deno is a secure, modern JavaScript and TypeScript runtime. It is created by the same developer who created Node.js, Ryan Dahl. Deno is built on the same V8 JavaScript engine as Node.js, but it provides an improved security model, better performance, and a more robust standard library. Deno also supports TypeScript, allowing developers to write their code in a type-safe language, which can then be compiled down to JavaScript for execution. Deno is designed to be a lightweight, secure, and efficient way to develop web applications.