Understanding the Difference Between package.json and package-lock.json

What is package.json?

The package.json file is the manifest file of your Node.js project.
It contains:

• Metadata about your project (name, version, description, author, etc.)
• Scripts you can run (like start, build, test)
• Dependencies and devDependencies, listed with version ranges (^, ~, etc.)

This file is created manually (via npm init) and is meant to be human-readable and editable.

What is package-lock.json?

The package-lock.json file is automatically generated when you run npm install.
It:

• Locks the exact versions of every dependency and sub-dependency
• Ensures consistent installs across different machines and environments
• Makes installation faster by skipping version resolution (since it’s already defined)

Feature	package.json	package-lock.json
Purpose	Defines project metadata & dependencies	Locks exact versions for reproducible installs
Created by	Developer (manual / npm init)	npm (auto-generated on install)
Versioning	Version ranges allowed (^, ~)	Exact versions of all dependencies
Human editable?	Yes	No (should not be manually edited)
Consistency	Not guaranteed	Guaranteed same versions everywhere
Install speed	Slower (needs to resolve versions)	Faster (uses already resolved versions)
Commit to Git?	Yes (mandatory)	Yes (highly recommended)

Why Both Files Are Important

• package.json provides flexibility: it allows updates to newer minor/patch versions of dependencies.
• package-lock.json ensures stability: every developer and production environment installs exactly the same versions, avoiding “it works on my machine” problems.