The goal of subnetting is to create a fast, efficient, and resilient computer network. As networks become larger and more complex, the traffic traveling through them needs more efficient routes. If all network traffic was traveling across the system at the same time using the same route, bottlenecks and congestion would occur resulting in sluggish and inefficient backlogs.

Creating a subnet allows you to limit the number of routers that network traffic must pass through. An engineer can create smaller mini-routes within a larger network to allow traffic to travel the shortest distance possible.

There could be hundreds of thousands of devices that are connected within a network, and the corresponding IP addresses can create a complex route that traffic must travel. Subnetting limits the IP address usage to within a few devices. This allows an engineer to use subnetting to create sub-networks, sorting data so that it can travel without touching every part of the more complex routers. To do this, an engineer needs to match each IP address class to a subnet mask.

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