Define the term "subnetting."

Subnetting refers to the process of dividing a larger network into smaller, more manageable sub-networks or subnets. This practice is essential in networking as it allows for improved organization, security, and effective utilization of IP address space. By creating subnets, network administrators can optimize routing, reduce broadcast traffic, and segment networks based on logical or geographical criteria. Subnetting helps enhance network performance and security by isolating groups of devices, allowing for better traffic management and control.

The other options do not accurately capture the essence of subnetting. Merging multiple networks would relate more to network integration rather than subdivision. Securing network devices focuses on the protection of equipment and information rather than partitioning networks. Encrypting data within a network pertains to data security through encryption methods, which is unrelated to the structural organization of a network.