They are used for to ask the same questions over a wide area with a lot less effort. Then to ask questions through interviews.

It narrows down the questions down to the person that needs to answer it. For example you think

Facebook is web 2.0?  

What is web 2.0?

Is G mail wed 2.0?

How can you use web 2.0 help on everyday life?

Is web 2.0 good or bad for you? Why?

What is it most known for? How?

Is Mine-craft web 2.0?

why is it web 2.0?

Is playing out side web 2.0?

Why is it not or is it.?

do you like web 2.0?