Most people know what a foil is; strands of hair are weaved and placed into foils with your selected color, resulting in the same level of lightened/colored hair throughout each strand. If someone wants to achieve a light blonde towards the ends, they will also the same result towards the roots. The danger is that if the hair ends are thinner, one can end up with even more lightened/colored hair at the roots.
Balayage, in contrast, can give a natural, a multicolored, and/or a dimensional effect by creating very natural-looking highlights which grow out with a much less noticeable and obvious root. The highlights/lowlights are painted in, lending endless creativity to the hair colorist.
Many celebrities get their hair balayaged and, in response to popular demand, Emerson Salon is offering this service as well. “The technique emerged in Paris in the ’70s; the word ‘balayage’ is French for ‘to sweep,’ a reference to the way in which the color is applied. After crossing the pond to the United States, balayage became extremely popular in the late 1990s.’” [http://www.wisegeek.com/what-is-balayage.htm]
Here are some photos of my balayage model, Carrie. Carrie is a full-time student who also works, and she needed something that would be easy to maintain, while still looking fresh and hip:

