Design is not a monolithic domain, and so, this chapter addresses the following questions:

• What are the branches of design knowledge and practice?
• What are the shared design principles and challenges they address?

Marcus Vitruvius Pollio, better known as Vitruvius, addressed these questions 2000 years ago. While he focused on architecture, much of what he wrote about applies to the most advanced Experience Design technologies being developed today, and the ideas are as valid as they have been since he wrote them and throughout history.

Vitruvius was a Roman architect who is known as the author of De architectura, or Ten Books on Architecture, which he dedicated to Augustus Cesar. The book is the earliest written work on architecture we know about. It was a "best seller", although, at the time, the manuscript had to be hand-copied for additional copies to be distributed. At some point after its publication, awareness of the book faded, and it only resurfaced again in 1414. It has been in print ever since. You can easily get a printed copy of this ancient manuscript from the library, or download a digital copy online.

By the time Vitruvius wrote his book in the first century CE, the Romans, Greeks, and Egyptians of antiquity had already reached remarkable heights of technical and aesthetic achievements, so Vitruvius was able to draw on the body of knowledge accumulated over centuries.

Architecture was the first discipline to formalize a thought and practice process that combined practical engineering considerations with aspirational design objectives. In other words, architecture has emerged as the first multi-disciplinary domain of knowledge and practice. As such, it has completely transformed the experiential relationship between people and their landscape.

Today, many of the design disciplines mentioned in Ten Books on Architecture have evolved, and new ones have been created. The term architecture is now applied to many of the disciplines that are part of modern design, including software architecture, information architecture, experience architecture, and so on. Currently, the Wikipedia page for "Design" lists no less than 39 disciplines, but some might still find the list quite incomplete.

Experience Design is a multi-disciplinary practice and the outcomes of design fuse the product's function and meaning. Consequently, it is difficult to organize design disciples in neat hierarchical buckets because they blend in ways that make it impossible to discern any linear relationship. They all have a role in impacting our experience, senses, and thoughts.

This line of thinking is finally being fully embraced by companies and organizations, as well as academic departments and professional organizations involved in design teaching and research. This chapter is an introduction to the major design disciplines that literally shape our lives, an a homage to Vitruvius and the multi-disciplinary approach he advocated so long ago.

This is a journey that closely follows human evolution as a species and culture, going back thousands of years. Some disciplines preceded others, have a long, rich history and amazing artifacts that survive to this day, while others literally emerged a couple of decades ago and produce artifacts with a life span measurable in months.

Although each discipline uniquely contributes to the domain of Experience Design, many of the principles and methodologies of design are common, as are the debates around the theoretical and practical mission of design.