This module or an Ethernet Shield uses the W5100 chip which provides a set of TCP/IP protocols, MAC (Media Access) and PHY (Physical Interface) in one network chip, with support for the SPI bus interface.
The Ethernet Arduino IDE library that comes with the Arduino IDE is designed directly for W5100 and is supported on this product.
Your Arduino can be a Web Server with this brick! See an example HERE: But start out with “Your First Web Server” below.

NOTE: There are RED and GREEN versions of this module; they work and wire up the same..

There is on-board voltage regulation, so you can use 5-12V VCC input. The signal pins support both 3.3V and 5V levels.
The Ethernet Module has a standard RJ-45 connection, with an integrated line transformer. Another similar version exists with “Power Over Ethernet” connections that use the pins marked P+, P-, and G; this one does not use those.

NOTE: Most Ethernet Shields using the W5100 chip will work the same in the examples below.

W5100 Ethernet Module Information:

Source: arduino-info – Ethernet