Node runs JavaScript on your computer.
Most beginner projects in this playbook (web apps, Chrome extensions, Expo) are JavaScript. Node is what runs and builds them. Install the LTS version.
Six Things To Recognise
node
The engine that runs JavaScript outside a browser.
npm
The installer for other people's code packages.
package.json
The project's recipe: what it needs and how to run it.
node_modules
The downloaded packages. Big. Never commit it.
npm install
Download everything the recipe lists.
npm run dev
Start the project on your machine.
package.json is the recipe. npm install does the shopping.