Building software today means standing on the shoulders of giants. NPM makes that possible.
1Dependency vs DevDependency
Dependencies are required for your app to run (e.g., Express). DevDependencies are only needed during development (e.g., Jest, ESLint). Keeping them separate reduces the size of your production environment.
2The node_modules black hole
This folder contains all the code you've downloaded. You should never commit it to Git—that's what the package.json file is for. Anyone can recreate the folder by running npm install.
3Semantic Versioning (SemVer)
NPM uses SemVer to manage updates. A version like ^4.18.2 means you allow updates that don't break compatibility (minor and patch updates), protecting your app from sudden breaking changes.
