Models of the process of design are relatively common. Each describes a sequence of steps required to design something—or at least the steps that designers report or recommend taking. Models of the process of design are common because designers often need to explain what they do (or want to do) so that clients, colleagues, and students can understand.

Less common are models of the domain of design—models describing the scope or nature of practice, research, or teaching. Such models may be useful for locating individual processes, projects, or approaches and comparing them to others. Such models also help clients, colleagues, and students understand alternatives and agree on where they are (or want to be) within a space of possibilities.

Typically models of a domain are of three types:

1. Timelines
   • Lists of events from the domain’s history
   • Links between events suggesting influences
2. Taxonomies
   • Lists of sub-domains
   • Trees branching into categories and sub-categories and so on
3. Spaces
   • Venn diagrams indicating overlapping categories
   • Matrices defining the dimensions of a space of possibilities or area of potential

The Space of Design