A network is any two things bound together. In our case, a network is two or more nodes (master or slave devices) that communicate. At its simplest, a network could be two people talking on a street corner. At the most complex, a network could be the entire Internet. The only real difference between the two is size and topology.
In networking, topology refers to the shape of the network or the way the nodes are interconnected. When referring to topology, you'll hear terms like "daisy-chain", "trunk and taps", or "star". In most cases the topology is defined by the networking hardware and system requirements. There are advantages and disadvantages to each topology. Some networks, Ethernet for example, can be configured in different topologies, whereas others may be limited to one.