What’s the best way to know if your idea is a good one?

Paul Graham (Co-Founder & Partner at Y Combinator)
Startups in 13 Sentences

Understand your users. You can envision the wealth created by a startup as a rectangle, where one side is the number of users and the other is how much you improve their lives. The second dimension is the one you have most control over. And indeed, the growth in the first will be driven by how well you do in the second.