A communication protocol is an agreement which specifies a common language two computers use to exchange messages. For instance, a protocol denotes the exact format and meaning of each message which a computer can send. It also indicated the conditions under which a computer must send a given message and how a computer must respond while a message arrives. Distinct types of protocols are used in Internet like IP & TCP. A computer linked to the Internet needs both TCP & IP software. IP provides a way of transferring a packet from its source to destination and TCP handles the lost data grams and delivery of data grams.