The --save option for npm install or npm i allows you to add the npm module you’re installing to the file package.json. This way it’ll become one of the project dependencies and will be automatically installed the next time you run npm install.

Let’s take a look at an example and install the module canvas with the --save option.

npm install --save canvas

Once you execute the line above in your terminal, the module canvas will be installed to node_modules and a new line will be automatically added to package.json.

"canvas": "^2.6.1"

Now, canvas became one of the project dependencies that are tracked in package.json.

You can learn more about what the caret ^ means next to the version ^2.6.1 here.