This is the port that your computer can use to comunicate with your network such as other computers or your router via a wired connection.
Integrated 10/100/1000MBPS
It's built in to your motherbaord! Asus & Gigabyte use the same network card on all of their motherboards so they are all the same. This is a normal wired connection which is much faster than a wireless card but does physically need a cable plugged in. Compatable with homeplugs and powerline adaptors. If you want wireless connectivity to your network then check out the next option down entitled "wireless network card".