This Ethernet Shield allows an Arduino board to connect to the internet. It is based on the ENC28J60 ethernet chip providing a network (IP) stack capable of both TCP and UDP. Please note that this is the NOT the typical WIZNET5100 chip that is native to the Arduino 1.0 library, you must install and use the alternative libraries.
The ethernet shield connects to an Arduino board using long wire-wrap headers which extend through the shield. This keeps the pin layout intact and allows another shield to be stacked on top.
This shield adds a micro-SD card slot and supports Power Over Ethernet (POE) using this DC power injector.