Who are those people applauding at the NYSE during opening and closing bells?

Julio C: Who are those people applauding at the NYSE during opening and closing bells?
When the New York Stock Exchange bell sounds, especially when at closing hour, there are some people, sometimes many, sometimes few, that just stand there and Applaud. Who are they and why do they applaud?

Answers and Views:

Answer by alberto J
Depend on the day, everyday is different people, but usually if there is an IPO the people ringing the bell will be the representative of these companies.
The higher the profile of the IPO the more the midia will show over and over the opening bell. Try remembering the day google went public, they showed so many times it made me sick.