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.
Trulia did something very similar to Bills.com with their landing page. It starts with a simple form asking for "an address" (which sounds less creepy than "your address," although that's what they mean). Below this simple form field is a bright orange button that contrasts well with the hero image behind the form, and emphasizes that the estimate will be personalized to your home.