• physical scope
• administrative methods
• operating systems
• interaction types
• protocols
• topology
• architecture

While most of these categorizations can't really be made as neatly as one might hope, engaging in such efforts can increase insight into the advantages and disadvantages of different aspects of networks.

The difficulties of actually categorizing networks based on certain characteristics abound. 

• For example, most networks have client machines running a pretty large variety of operating systems software.  Even the operating systems can change within different segments of a network.
• Networks often have mixed topologies.
• Networks can have a variety of architectures.
• Physical scope can be a pretty hard notion to define clearly

But, in spite of these difficulties we will still make efforts to clarify these notions and categories in the nest group of web pages.