npm is a tool commonly used by JavaScript projects to install and manage reusable packages. A package is a bundle of code or tools made available for a project to use.
For example, a website may rely on a package that helps display icons. The project lists the packages it needs, and npm can download them so the website can be built or tested on a computer.
Packages can come from outside the project, so install only ones you trust and check what a command will do. npm is also the name of a large online package registry where many JavaScript packages are shared.