Variable Length Subnet Masking (VLSM) is a subnetting technique that allows different subnets within the same network to have varying subnet mask lengths based on specific requirements. Unlike traditional fixed-length subnetting, where all subnets have the same size, VLSM enables more efficient IP address allocation by assigning larger subnets to networks with more hosts and smaller subnets to networks with fewer hosts. This method helps reduce IP address wastage, optimizes network performance, and improves scalability. VLSM is commonly used in enterprise networks and routing protocols like OSPF and EIGRP, allowing for more flexible and efficient use of IPv4 addresses. Learn more: https://en.wikipedia.org/wiki/VLSM