350,000 packages.
NPM is a package manager for Node.js packages, or modules if you like.A package in Node.js contains all the files you need for a module.Modules are JavaScript libraries you can include in your project.
Example--
var http = require('http');
var uc = require('upper-case');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/html'});
res.write(uc.upperCase("Hello World!"));
res.end();
}).listen(8080);