NPM, or Node Package Manager, is a fundamental tool in the JavaScript programming ecosystem, primarily used for managing packages in Node.js projects. Functioning as both a command-line utility and an online repository, NPM simplifies the process of sharing and consuming code. It allows developers to download and install third-party packages from the NPM registry, a vast database of open-source solutions for various coding problems. By executing simple commands, developers can add, update, or remove dependencies in their projects, ensuring efficient management of the codebase.