Sending data from one computer to another over the Internet is accomplished via Internet Protocol (IP). Every computer (or “host”) connected to the Internet has at least one unique IP address that identifies it amongst all of the other computers accessing the Internet.
When you send or receive data, whether it’s an incoming email or you’re accessing a web page, the data is sliced into small parcels known as “packets.” Both the sender’s and receiver’s IP address is contained in that packet.
All packets are first sent to a “gateway” computer which “understands” a portion of the Internet. After reading the destination IP address, the first gateway computer forwards the packet to an adjacent gateway, which again reads the destination address -- and so on and so on across the Internet until a gateway recognizes the packet is destined to a computer within its immediate neighborhood or domain. That final gateway then forwards the packet directly to the specified computer address.
The division of a single message into multiple packets can result in the arrival of packets no particular order, since each packet may be sent by differing routes across the Internet. The Internet Protocol just delivers them; it is another protocol, the Transmission Control Protocol (TCP), which places them back into the appropriate order.
There is no continuing connection between the IPs at the end points, which means IP is also referred to as a “connectionless protocol.” Each packet traveling across the Internet is viewed as an independent unit of data with no relation to any other data unit until a TCP, the connection-oriented protocol, puts the packets in the proper sequence. In an Open Systems Interconnection (OSI) communication model, IP resides in Layer 3, the Networking Layer.
Today, Internet Protocol Version 4 (IPv4) is the most widely used IP version; however, IP Version 6 (IPv6) is beginning to receive provider support. IPv6 allows for much longer IP addresses and, therefore, for the possibility of many more Internet users. Since IPv6 includes all the capabilities of IPv4, any server that can support IPv6 packets will also support IPv4 packets.