What is the way to replace frames on a website?

[Richard Miller]

I want to build a new website heavily driven by LC & cgi. It needs to 
appear to use frames so that content is instantly updated throughout a 
given web page without having to reload the entire page. But I know not 
to use frames. What's the best alternative?

iFrames?
CSS?
divs?
php?

I'd REALLY prefer to use a revlet. Too bad that alternative seems less 
and less practical these days.

Thanks.
Richard Miller