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A Data Packet is a formatted block of data sent across a [[Computer Network]].

==Packet Header==
Each individual Data Packet includes a Packet Header, containing information on the packet's destination, thereby informing the [[Nodes]] where to send the data packet. The header includes the following information about the packet's destination:
*The [[IP Address]] number, which identifies the [[Computer]] the data is to be sent to
*The [[Port]] number, which identifies a particular [[Process]] running on the destination Computer

The computer's [[IP Address]] is like the street address of an apartment building, while the [[Port]] number is like the number of a particular apartment within the building.

The [[IP Address]] and the [[Port]] number together make up an [[Internet Socket]], which is one of the end-points of a two-way communication flow between specific application processes running on two different devices connected to the Internet. 

==Packet Forwarding and Packet Routing==
Data Packets are [[Packet Forwarding|forwarded]] from one [[Network Segment]] to another by [[Nodes]], and [[Packet Routing|routed]] to their final destinations.

[[Packet Forwarding]] takes place just from one [[Node]] to the next, while [[Packet Routing]] selects the path of links over which to send the packet towards its final destination.

Packet Forwarding is handled at lower [[network layer]]s, while Packet Routing involves higher Network Layers. Forwarding and routing are generally described in terms of one or the other of the two standard [[network protocol]]s: the [[Internet protocol]] or the older [[OSI protocols]].

==See Also==
*[[IP address]]
*[[Port]]
*[[Internet socket]]
*[[Packet forwarding]]
*[[Network protocol]]

==External Links==
*Wikipedia article about data packets: http://en.wikipedia.org/wiki/Packet_%28information_technology%29
*Wikipedia article about IP addresses: http://en.wikipedia.org/wiki/IP_address
*Wikipedia article about ports: http://en.wikipedia.org/wiki/TCP_and_UDP_port
*Wikipedia article about internet sockets: http://en.wikipedia.org/wiki/Internet_socket

[[Category:Network protocols]]