The zone of communication in a wireless network is called a CELL.
When there is one cell, the configuration is referred to as a BSS (Basic Service Set). When there are multiple set the term used is ESS (Extended Service Set.)
Ad Hoc
For networks with few nodes many people choose to set up an Ad-Hoc network. This type of network is a peer-to-peer network. The nodes of the network talk to each other with out the help on a centralized coordinator (called an Access Point)
Infrastructure
For network with many nodes and a desire to have advanced features you would set up an Infrastructure. This type of network has an access point (or access points) which coordinates traffic. Multiple Access Points can be used to have a large amount of nodes in an area by each broadcasting on its own know Frequency Hopping Spectrum. Also an Access point can link the wireless network to a wired LAN or to other wireless LANs via a wireless bridge.
