ip add 192.168.100.2 and subnet mask 255.255.255.0 now 192.168.100.X is network id which is used to identify from which network u belongs to and x is host id which is unique for every node on network

network id and host id both are unique

network address is a sfecific idetifide with host in hole network

host address is a within network a sfecifide protocal  address.

The Network address identifies the specific network to which host is attached, and Host address uniquely identifies a host within a network.

The distinction is important because router routes the packet according to a network address and don't care about host address.