An idea is just an impulse to do something in some way. &quot;A social network&quot; is an idea. But then you have to come up with decisions about how exactly it will work. Will people have their own backgrounds and widgets? Or will we just give everyone the same style? Let&#x27;s add a poke counter. That&#x27;s an idea, too. Let&#x27;s add a positive and negative counter. Even more ideas.<p>When people say ideas are cheap, they mean cheap in relation to execution. For each idea you have, you need some way to decide whether to continue coming up with related ideas. And that almost always involves getting feedback from the universe about what you&#x27;ve already considered. And that takes effort. Finding out whether someone will fund your idea requires you to make a presentation. Finding out whether someone will sign up to your social network will require software and hardware.<p>Dreaming about what might happen if someone gives you money and a bunch of people sign up to your network IS cheap. You will inevitably have more possibilities than you can actually test in the market.<p>I&#x27;m partly biased due to a bad experience with an old partner about this. I&#x27;d spent most of a year building a prototype, and he sat down next to me and said &quot;that thing about letting the customers do so-and-so was my idea, and I want acknowledgement for it.&quot; He wasn&#x27;t the guy who actually built the thing, found the customer, and got the customer to say they wanted it.