Ideas that spread

How many businesses have you seen fail because there was no easy way to tell your friends what they actually do? How many ideas have you seen die because there was no easy way to explain them? How many projects lost traction because no-one could clearly state what they were for?

Your audience is very unlikely to want to figure this out for you. If you want your idea to spread, your chances will dramatically increase if you yourself work out a way that makes it easy to spread.

So, what should spread for your idea? What should people think when they think about you? What should they say when they pass your message along to their friends?