OK, but how is stuff sent from my computer to, say, Yahoo!?
A. First off, your computer does a lookup – using a service called DNS (Domain Name Service) to convert www.yahoo.com to a numeric value, such as 66.218.71.80. Then it builds a collection of characters that says send this data from me, 192.168.0.1 to Yahoo at 66.218.71.80. This is called a packet. That gets wrapped in an Ethernet frame (addressed from 00:40:05:DE:AD:00 to the MAC address of the local gateway router, 0:d0:9e:6:38:00 and squirts it out the router. Packets are forwarded step by step along a path from you to Yahoo by computers called routers. This is done based on the 32 bit IP address and the router’s knowledge of the network. Each router sees a Ethernet frame addressed to it (by MAC address), checks the TCP/IP address to figure out where to send it next, re-wraps the TCP/IP packet in a new Ethernet frame (with the from MAC as it’s own and the to MAC as the next hop). This happens until the TCP/IP packet reaches the final segment (the last router). Once it reaches a route
