Deno is a modern runtime for executing JavaScript and TypeScript outside of a web browser. Created by Ryan Dahl, the original developer of Node.js, Deno aims to improve upon its predecessor by offering a more secure and user-friendly environment. It includes built-in support for TypeScript, making it easier for developers to work with this popular programming language. One of Deno's key features is its secure by default approach, which restricts file, network, and environment access unless explicitly allowed. This enhances security for applications and helps prevent potential vulnerabilities. Additionally, Deno has a simplified module system that allows developers to import modules directly from URLs, streamlining the development process.