1) With this Ethernet Shield, your Arduino board can be connected to internet easily.
2) Can be used as a web server or client.
3) It is directly supported by Arduino official Ethernet Library.
4) Based on the Wiznet W5100 Ethernet Chip.
5) The Wiznet W5100 provides a network (IP) stack capable of both TCP and UDP.
6) It adds a micro-SD card slot, which can be used to store files for serving over the network.
7) It is directly supported by Arduino official SD Library.
8) It is compatible with the Arduino Uno as well as Mega.
9) Reset button.
10) Power, pin13, ethernet status LED indicator.
11) Dimension: 54 x 73 mm.