The last octet allows for up to 254 systems on each Ethernet. Note that 128.6.4.194 and 128.6.5.194 would be different systems. Of course we normally refer to systems by name, rather than by Internet address. When we specify a name, the network software looks it up in a database, and comes up with the corresponding Internet address. Most of the network software deals strictly in terms of the address.
Information is transfered in packets .
Each of these packets is sent through the network individually. There are provisions to open connections to systems. However at some level, information is put into packets, and those packets are treated by the network as completely separate. For example, suppose you want to transfer a 15000 octet file. Most networks can't handle a 15000 octet packet.