Node Package Manager (npm) is the default package manager for JavaScript and is widely used in web development. It allows developers to easily share, install, and manage code libraries (packages) and their dependencies for JavaScript projects. npm simplifies the process of integrating third-party tools and frameworks by providing a vast public registry of reusable code. It also offers tools for version control, security auditing, and script automation, making it essential for modern JavaScript development workflows. npm is bundled with Node.js, enabling seamless integration and management of both server-side and client-side packages.