The first IP address of an IP subnet is the network address, which stands for the whole network, while the last address is the broadcast address.
As far as I understand, we never really send packets to the network address, it's purely symbolic, for use in firewall rules etc., to mean the whole IP range of the network.
Is this correct, or does it sometimes happen that an actual IP packet has a network address (first address of the subnet) as its source or destination IP address?