Design is not just what it looks like and feels like. Design is how it works. — Steve Jobs
design : to make decisions about (something that is being built or created) : to create the drawings, etc., that show how (something) will be made — Webster
Design is a plan for the creation of something or for the implementation of an activity. The design usually has to satisfy certain goals and constraints, may take into account aesthetic, economic, socio-political or other types of considerations. — Wikipedia
A person who produces a design is called a designer, which is a term generally used for people who work professionally in one of the various design areas—usually specifying which area is being dealt with (such as a fashion designer, product designer, web designer or interior designer), but also others such as architects and engineers. A designer’s sequence of activities is called a design process, possibly using design methods. The process of creating a design can be brief (a quick sketch) or lengthy and complicated, involving considerable research, negotiation, reflection, modeling, interactive adjustment and re-design.
Here are links to pages about closely related subjects.
Philosophy Metaphysics, Logic, Epistemology, Ethics, Aesthetics
System, Cycle, Structure, Growth, Complexity, Control, Disturbance, Entropy, Chaos
Process, Manage, Design, Prototype, Implement, Assess, Revise, Maintain