The basic idea

...is this: A program that will adapt a website to its users by trial and error. It should be a systemization of something that every website creator/designer/owner already does -- making changes, seeing what effect they have, and keeping the beneficial ones. In biological terms, variation and selection. In engineering terms, an adaptive system. In statistical terms, Bayesian updating. In scientific terms, controlled experimentation. The core idea must be as old as common sense. The new part is making a computer do it for you in the environment of the web.