Donald A. Norman Living with Complexity#"I distinguish between complexity and complicated.
I use the word “complexity” to describe a state of the world.
The word “complicated” describes a state of mind.
The dictionary definition for “complexity” suggests things with many intricate and interrelated parts, which is just how I use the term.
The definition for “complicated” includes as a secondary meaning “confusing,” which is what I am concerned with in my definition of that word. I use the word “complex” to describe the state of the world, the Appropriate complexity.
To the average person, the cockpit of a modern jet airplane is incredibly complicated and confusing. Not for the pilots: to them, the instruments are all logical, sensible, and nicely organized into meaningful groups. "