In Node.js, dependencies, devDependencies, and peerDependencies are categories of packages listed in the package.json file, each serving a specific purpose:
Dependencies
These are the packages required for your application to run in production.
They are installed when you run npm install without any additional flags.
DevDependencies
These are the packages needed only during the development or testing phase, such as linters, test frameworks, and build tools.
They are installed when you run npm install in a development environment but are not included in the production deployment.
PeerDependencies
These specify packages that your package is compatible with but does not directly include.
This is often used for plugins or libraries that require a specific version of a host package, leaving the user responsible for installing the required version.
Each type helps manage your project’s dependencies efficiently, depending on how and where they are needed.