Node.js How modules are loaded Global Mode
Example
If you installed Node using the default directory, while in the global mode, NPM installs packages into /usr/local/lib/node_modules. If you type the following in the shell, NPM will search for, download, and install the latest version of the package named sax inside the directory /usr/local/lib/node_modules/express:
$ npm install -g express
Make sure that you have sufficient access rights to the folder. These modules will be available for all node process which will be running in that machine
In local mode installation. Npm will down load and install modules in the current working folders by creating a new folder called node_modules for example if you are in /home/user/apps/my_app a new folder will be created called node_modules /home/user/apps/my_app/node_modules if its not already exist
