Just as if you were trying to sell a car with a lien on it. Your residual is of course higher towards the beginning of the lease than at the end.

To the question of what makes leasing attractive:

1) lower payments. No need to expound on this one.

2) easy out. Basically you have a guaranteed buyer and a set purchase price at the end of the lease. During the lease you are also likely to carry less negative equity if you decide to sell it early. This is mainly because you are not paying all of your tax up front on a lease like you would a purchase.

3) easier in than financing. Basically you are only putting the depreciation on your credit not the whole car. This makes it easier for people to get approved even without perfect credit.

4) hassle free ownership. It's under the bumper to bumper warranty.

5) Can be cheaper purchase option long term for those planning to hang on to the car forever. If you have great credit and can afford the car payment over 60 months, financing the car Will almost always be cheaper. However if you are pushing a loan out to 7 years and paying 5-6% interest, you are probably better off leasing at a low money factor for 3 years then buying out the lease at a lower 4-5 year interest rate.

Now the caveats. If you are planning on driving a ton of miles, leasing is probably not the best option. Also car manufacturers set their own residuals, which means a residual may or may not be based in reality. Honda's residuals are generally a fairly accurate reflection of the auction value of the car in 3 years.

Sorry for the super long post. Hope that helps.