Can you explain what npm is and what it is used for in development?

npm (Node Package Manager) is a package manager for the Node.js platform. It is used to manage libraries and dependencies in JavaScript projects.

Main functions of npm:

• Allows installing, updating, and removing packages (libraries) from the central npm repository.
• Manages project dependencies through the package.json file.
• Provides the ability to publish your own packages.

Example usage:

npm init           # initialize a new project with package.json
npm install express # install the express library
npm install        # install all dependencies from package.json

Thus, npm facilitates code reuse and management of external libraries in Node.js and frontend development.