I’ve checked out a few of Russell Brunson’s content, on youtube, and he seems to really know his stuff. To be honest, at first I was skeptical and thought he could be a fraud but then I had a read of his book. It was actually really interesting and full of useful advice, also I seen that he’s speaking at Grant Cardone’s 10X seminar (or something like that), I know he’s legit so Russell – and his program – must be too!
A/B testing, or A/B split testing, is a method for testing two versions of a webpage: version "A" and version "B". The goal is to test multiple versions of webpages (e.g., home page vs. product page) or one specific element that changes between variation A and variation B (such as having a lead form on the left hand side or having it placed on the right hand side), FAQ to determine which version is most appealing/effective. This testing method may also be known as A/B/n split testing; the n denoting more than 2 tests being measured and compared. The data for A/B testing is usually measured via click-through rate or an alternative conversion tracking method.[11]
However, what Brunson cleverly conceived with ClickFunnels is to create a SaaS that can integrate with the world's most popular platforms and virtually anyone can quietly launch a funnel in hours as opposed to weeks of hefty coding and programming. As a fervent user of ClickFunnels myself, I can tell you that the system is impressive beyond measure. 

Clickfunnels: Review, Demo, Pricing and Features: