A worked example
192.168.1.100/24 belongs to the network 192.168.1.0, with a broadcast address of 192.168.1.255 and 254 usable host addresses from 192.168.1.1 to 192.168.1.254.
Frequently asked questions
What's the difference between the network address and the first usable address?
The network address (all host bits zero) identifies the subnet itself and isn't assignable to a device. The first usable address is one number higher — the first address actually available to assign to a host.
Why does the broadcast address get reserved too?
The broadcast address (all host bits set to one) is used to send a single packet to every host on the subnet at once — because it has this special purpose, it's excluded from the assignable host range, just like the network address.
What does CIDR notation like /24 mean?
It's shorthand for the subnet mask — the number after the slash tells you how many of the 32 bits in an IPv4 address are fixed as the network portion. /24 means 24 network bits and 8 host bits, equivalent to a 255.255.255.0 mask.