TCP IP is a set of rules that enables different types of computers and networks on the Internet to communicate with one another. TCP/IP was originally developed by the United States Department of Defense for computers using the UNIX operating system, but it is now used by every computer, regardless of operating system, on the Internet. TCP defines how data are transferred across the Internet to their destination. IP defines how data are divided into chunks, called packets, for transmission; it also determines the path each packet takes between computers.
A packet is the basic unit of data transferred over a network such as the Internet. A message to be transferred over the network is broken up into small units, or packets, by the sending computer. The packets, which travel independently of one another, are marked with the sender's address, destination address, and other pertinent information, including data about any errors introduced during the transfer. When the packets arrive at the receiving computer, they are reassembled.
Data Transfer is the movement of information from one location to another, either within a computer (as from a disk drive to random access memory) or between a computer and an external device (as between two computers or a file server and a computer on a network). The speed of transfer is called the data rate, or data transfer rate, and is usually measured in bits per second, or bps. The raw data rate (the maximum transfer speed) is usually considerably higher than the actual rate at which meaningful data is transferred because of idle time, error-checking procedures, and other overhead. Also, data transfers from different sources to different destinations often compete with each other if they use the same data path�for example, on a network, or on a bus in a computer system.
In a TCP/IP environment, end stations communicate with servers or other end stations. This can occur because each node using the TCP/IP protocol suite has a unique 32 bit logical address. This address is known as the IP address. Each company or organization connected to an inter-network is perceived as a single unique network that must be reached before an individual host within that company can be contacted. Each company network has an address; the hosts that live on that network share that same network address, but each host is identified by the unique host address on the network.
There are three classes of IP addresses that an organization can receive from the American Registry for Internet Numbers (ARIN) (or the organization's ISP). They are Class A, B, and C. ARIN now reserves Class A addresses for governments throughout the world (although a few large companies, such as Hewlett Packard, have received one in the past) and Class B addresses for medium-sized companies. All other requestors are issued Class C addresses. IP addresses identify a device on a network and the network to which it is attached. To make them easy to remember, IP addresses are usually written in dotted decimal notation. Therefore, IP addresses are 4 decimal numbers separated by dots. An example of this is the address 166.122.23.130. Keep in mind that a decimal number is a base 10 number, the type we use in everyday life.
In a TCP/IP environment, end stations communicate with servers or other end stations. This can occur because each node using the TCP/IP protocol suite has a unique 32 bit logical address. This address is known as the IP address. Each company or organization connected to an internetwork is perceived as a single unique network that must be reached before an individual host within that company can be contacted. Each company network has an address; the hosts that live on that network share that same network address, but each host is identified by the unique host address on the network.
Subnets improve the efficiency of network addressing. Adding subnets does not change how the outside world sees the network, but within the organization, there is additional structure. Routers determine the destination network by using the subnet address, which limits the amount of traffic on the other network segments. From an addressing standpoint, subnets are an extension of a network number. Network administrators determine the size of subnets based on the expansion needs of their organizations. Network devices use subnet masks to identify which part of the address is for the network and which part represents host addressing.
Putting it all together at a basic level, TCP IP is the combination of two independent protocols which control how packets of information are transferred (e.g. data transfer) from one computer or one network to another. Developed in the 1960s by the Advanced Research Projects Agency, TCP IP formed the basis of the internet by establishing a set of rules which enabled computers and computer networks to communicate with each other. TCP - Transmission Control Protocol - is a secure way of transmitting packets over a network or the internet. IP - internet protocol - does not require or demand acknowledgements that the packets were received by the receiving computer or network. Hence, IP is an insecure way of packet transmission. However, IP is faster than TCP and is used in some circumstances where reliability is less important than speed.