design is...

Design is you.
Design is me.
Design is that billboard.
Design is that building.
Design is your shoes and my shoes.
Design is the page in which these words appear.

So what IS design?

According to the Merriam-Webster Dictionary, design is a noun representing a particular purpose: a deliberate planning or a mental project or scheme.  But that's just what the book says. Truthfully, design is everything and anything. Design is what you want it to be.  There's no 'real' set definition of what it is, since it means differently from person to person.

Everyone is familiar with 'art' and the way the definition of art differs from person to person. Some people may think that Andy Warhol's works should not be considered art, while others simply adore his work.
(image credit: lateboots.blogspot.com)
Therefore, in the same way that art cannot be specifically defined, design cannot (and should not) be strictly defined either.  To define design would mean to limit the things one can do with it.

Sometimes when people think about design, people think of something "creative" and complex--such as the printing on a T-shirt.

And, of course, that is design! But design is so much more in addition to that! Design is the size of the shirt, the color of the shirt, the way it was sewn together!

Lets take a look at my alarm clock as another example of design in places we don't expect to see.

People may look at it, and just see it as that--an alarm clock. But if they were to stop and think about it, they'll see that there was a lot of design that went into creating the clock.  For example, consider the light of the clock. It's blue, rather than red or yellow or green.  And take a look at the shape of the alarm clock. it's an odd triangular shape, rather than a traditional rectangle.

In this example, I once hit upon color and shape as being part of design. But in general, design is a dense term! It encompasses color, size, shape, line, texture, value, and so much more!