IPv4 - TCP/IP Model
Majority of the internet uses a protocol suite called the Internet Protocol Suite also known as TCP/IP protocol suite. This suite is a combination of protocols which encompasses a number of different protocols for different purpose and need. Because the two major protocols in this suites are TCP (Transmission Control Protocol) and IP (Internet Protocol), this is commonly termed as TCP/IP Protocol suite. This protocol suite has its own reference model which it follows over the internet. In contrast with OSI model, this model of protocols contains less layers.
This model is indifferent to the actual hardware implementation, i.e. Physical layer of OSI Model. This is why this model can be implemented on almost all underlying technologies. Transport and Internet layers correspond to the same peer layers. All three top layers of OSI Model are compressed together in single Application layer of TCP/IP Model.
Internet Protocol Version 4 (IPv4)
Internet Protocol is one of the major protocol in TCP/IP protocols suite. This protocol works at Network layer of OSI model and at Internet layer of TCP/IP model. Thus this protocol has the responsibility of identification of hosts based upon their logical addresses and to route data between/among them over the underlying network.
IP provides a mechanism to uniquely identify host by IP addressing scheme. IP uses best effort delivery, i.e. it does not guarantee that packets would be delivered to destined host but it will do its best to reach the destination. Internet Protocol version 4 uses 32-bit logical address.