LESS - Dynamic Stylesheet Language

LESS is a dynamic stylesheet language meant to extend CSS with thing like variables, mixins, operations and functions. Please click here to find out more about LESS.

Why not Plain CSS?

I don't know which one is better LESS or the plain CSS. However, for now LESS is really comes down to customization and reuse of the code. But the question is raise in my mind that with the LESS, browser need to interpret and compile the LESS CSS class every times and which may decrease web page performance. So why LESS??

Please let me know your suggestion in comment and correct me if I misunderstood about LESS. It's really confuse me that what to choose LESS CSS or normal plain CSS.