Floor functions

[matrix_204]

Could someone explain me what floor functions are and what is their purpose? And how they work?
Also if you can give me an example of a function that has the floor function in it, it would be helpful.

[Galileo]

http://mathworld.wolfram.com/FloorFunction.html

The floor function \lfloor x \rfloor, also called the greatest integer function, gives the largest integer less than or equal to x. (So you're rounding x down to the nearest integer).

The site has the graph of this function plotted.