Clarify VRF's?

Wondering if someone could give me some clarity or further explain VRF's (layman's terms)? I know that some people relate VRF's to routers like VLAN's are to switches and that they separate traffic and for security purposes.

Reason I am asking is because our company uses VRF's to separate traffic / data from one department building from the other. Every time I inquire the only real explanation I get is that it helps each department stay within its own segment if you will and if a virus / security breach were to occur (let's say in the Customer Service dept) it would not bleed over into the Credit dept.

Can anyone shed some light and help me to understand the specific meaning / use / etc?

Thanks.....