Overview
Describe what it is that is creating an opportunity for a startup in the market area that you are addressing.
Cause
What change is creating a new opportunity? That change could be either a change in technology that's allowing you to provide a much better answer to an already-existing problem, or it could be a change that's creating a new need in the market that didn't exist before.
But there's usually some kind of change (possibly a disruptive change) that's creating an opportunity. Otherwise, it's not likely to be a fast-growing opportunity.
A Compelling Need
For the need to be sufficiently compelling to attract venture capital, you'll typically need to be addressing some new need that will drive a rapidly growing opportunity, or you'll need to be providing some new technology or approach to a problem that presents a very compelling advantage over what is available today
Who has the Pain?
If you're solving a problem, it's a problem that is causing someone pain. Who, out in the market, has the pain that you will address? Is there a way to quantify that pain for a typical individual? Across the entire market?