In 1981, RFC 791 outlined the specifications for IPv4, which had two principal tasks: addressing and fragmentation, as defined in section 1.4, operation, at https://tools.ietf.org/html/rfc791#section-1.4.

As stated, one of the original roles of IPv4 was fragmentation, which breaks packets apart. At the time, this was necessary because, in the early 1980s, most of the networks had limited bandwidth and were unable to transmit large packets.

Over time, efforts have been made to upgrade and replace the antiquated data pathways, and much of the internet has been replaced by high-speed, fiber optic cables. As a result, on today's networks, fragmentation is rarely used. 

As time has passed, we can see that IPv4 is still influential in addressing, along with the role of routing, in order to get data to its final destination.

IPv4 was standardized in 1983, and uses a 32-bit address space. Scientists identified at an early stage the need for a larger address space. IPv6 has a 128-bit address space and provides enhancements to the protocol in general, such as simplified network configuration and more efficient routing. There is a slow migration to IPv6, mainly because the use of private IP addressing on a LAN has extended IPv4's lifespan.

As a result, IPv4 is still widely used. So that you have the skills required to face everyday network-related issues when dealing with IPv4, in this next section, we will examine the header and the field values so that you can be confident when looking at a packet capture that you can quickly drill down to the issue.