In the most narrow sense, an idea is just whatever is before the mind when one thinks. Very often, ideas are construed as representationalimages; i.e. images of some object. In other contexts, ideas are taken to be concepts, although abstract concepts do not necessarily appear as images.[1] Many philosophers consider ideas to be a fundamental ontological category of being.
The capacity to create and understand the meaning of ideas is considered to be an essential and defining feature of human beings.
In a popular sense, an idea arises in a reflex, spontaneous manner, even without thinking or serious reflection, for example, when we talk about the idea of a person or a place.
The below video leads the potential of the sixth sense technology!
http://www.ted.com/talks/
Happy viewing!