Original : https://www.luisllamas.es/arduino-ethernet-shield-w5100/

WHAT IS THE W5100?

The W5100 is an Ethernet controller made by Wiznet specially designed for embedded applications. We can use this controller with a processor like Arduino to implement internet communication.

The W5100 is designed to make it easy to implement internet connectivity without the need for an OS, making it interesting for MCU and IoT applications.

Includes a hardware TCP/IP stack and 16Kbyte internal buffer for Tx/Rx. This allows the processor to be freed from these tasks, being one of its main advantages over other Ethernet controllers such as the ENC28J60.

The W5100 can be connected via SPI, making it easy to connect to most processors. Some modules incorporate an SD card reader, where we can save files (html, txt, jpg, png) to work with when we act as a server.