What do you think the most important thing to know about your customer is?

In your experience, what has been the biggest breakthrough piece of knowledge you've learned about your customer?

As Jim Carrey put it in Jim & Andy: "What do THEY want?"

Give the customer what he/she wants in a package of what he/she needs, see:… (that includes more insights)

What do they currently pay for? What will they actually pay for (as proven by what they have actually paid for)?