As delivered, your Arduino isn’t ready for Internet connectivity. It’s not far off, though. Believe it or not, you’re only an Ethernet adapter away from surfing the World Wide Web or serving up your own web pages with your humble little chip. There are two popular ways to go about this.
The standard Ethernet Shield for Arduino is based on the WIZnet 5100 chip. It plugs into the Arduino Uno like any other shield and has an Ethernet jack on one edge. The standard Ethernet library, as supplied by the Arduino software, has several example sketches, including both a WebClient and a WebServer application. So plug, plug, click, upload, and you’re in the web business. Not complicated at all, and almost a little too easy.
To make it more ...