Node.js is a Javascript engine (Google's V8 engine for Chrome, written in C++) that allows to run Javascript outside the browser. While numerous libraries are available for extending Node's functionalities, the engine comes with a set of core modules implementing basic functionalities.
[
'assert',
'buffer',
'c/c++_addons',
'child_process',
'cluster',
'console',
'crypto',
'deprecated_apis',
'dns',
'domain',
'Events',
'fs',
'http',
'https',
'module',
'net',
'os',
'path',
'punycode',
'querystring',
'readline',
'repl',
'stream',
'string_decoder',
'timers',
'tls_(ssl)',
'tracing',
'tty',
'dgram',
'url',
'util',
'v8',
'vm',
'zlib'
]