The notation "203.0.113.0/24" represents an IP address and its associated subnet mask. In this case, "203.0.113.0" is the base address, while "/24" indicates that the first 24 bits of the address are used for the network part. This means that the remaining 8 bits can be used for individual devices, allowing for up to 256 unique addresses within this subnet. This specific IP address range is part of the IANA reserved address space for documentation and examples. It is often used in tutorials and educational materials to illustrate networking concepts without using real, routable IP addresses.