If you're looking for a car, you would naturally visit a used-car dealer's lot. When you find the car you really like, you will have to decide how much you can afford to buy the car. You should only pay for the used car at a fair and reasonable price.
The used-car dealer will then show you what the price is as published by the Kelly BlueBook car price guide. (The KellyBlueBook prints more than a single price guide for used cars. But the used car dealer would most possibly only use the "Kelly Blue Book Auto Market Report Guide." This is the version of the KellyBlueBook that is sold to dealers by the Kelley company.)
Be aware that the car dealer will simply tell you that the asking price of the used car you're buying is much lower than what the kelly bluebook is suggesting. Furthermore, the auto dealer will present to you the value of the used car that you want in the KellyBlueBook. The dealer would then negotiate with you by informing you rather explicitly that you are getting the best car deal and that there is nothing to worry about as his asking price for the used car is quite reasonable and fair. This would probably lead you to believe that his offer is the best you can get in a car deal.
But such a deal is not always the best one, specially if you are new to the used-car buying process. You would soon learn that the price for the used car as listed on the KellyBlueBook is actually only an estimated price or "suggested retail value." The price list in the Blue Book only represents Kelley's estimated dealer asking price. The asking price may usually be notably higher than the selling price.
You must never ask the used-car dealer what price Kelly BlueBook thinks dealers are asking for the car that you want to buy. It is better to ask the dealer at what price the car is actually being sold for by other dealers.