Package Manager

A package manager is like an app store plus a shopping list. The third-party code your project needs (React, a component library, a chart library) is listed in package.json. Run npm install or pnpm install, and it downloads those packages into the node_modules folder.

The lock file (package-lock.json, pnpm-lock.yaml, yarn.lock) records the exact version of every package, so everyone installs the same thing. It should be committed to Git. node_modules is huge and shouldn't be committed.

A project should use just one package manager. The lock file tells you which one, and mixing them easily causes dependency conflicts. The scripts in package.json define common commands, like npm run dev. When the AI suggests installing a new package, it's fine to ask whether it's really needed.