Node Js Core Modules
Here is a brief of list of core modules:
The HTTP interfaces in Node.js are designed to support many features of the protocol which have been traditionally difficult to use. In particular, large, possibly chunk-encoded, messages. The interface is careful to never buffer entire requests or responses--the user is able to stream data.
HTTPS is the HTTP protocol over TLS/SSL. In Node.js this is implemented as a separate module.
File I/O is provided by simple wrappers around standard POSIX functions. To use this module do require('fs'). All the methods have asynchronous and synchronous forms.
Node.js has a simple module loading system. In Node.js, files and modules are in one-to-one correspondence (each file is treated as a separate module).
The querystring module provides utilities for parsing and formatting URL query strings.
A stream is an abstract interface for working with streaming data in Node.js. The stream module provides a base API that makes it easy to build objects that implement the stream interface
The readline module provides an interface for reading data from a Readable stream one line at a time
The repl module provides a Read-Eval-Print-Loop (REPL) implementation that is available both as a standalone program or includible in other applications.
The timer module exposes a global API for scheduling functions to be called at some future period of time. Because the timer functions are globals, there is no need to call require('timers') to use the API.
The url module provides utilities for URL resolution and parsing.
The zlib module provides compression functionality implemented using Gzip and Deflate/Inflate.