Although you have toured the property, looked at the walls and ceiling, turned on the faucets and played with the light switches, you have not lived in it. The seller has years of knowledge about his or her home and there may be some things you want to find out about as quickly as possible. For this reason, you will require certain disclosures as part of your offer.
Basically, you want the seller to disclose any adverse conditions that may have a substantial impact on your decision to purchase the home. This would include any problems with the house, whether the property is in a flood zone, a noise zone, or any other kind of hazardous area.
If you have an agent representing you, this is almost automatic, but many states do not require individuals selling their own home to provide you with this information. Often they do not require banks selling foreclosed property to provide these disclosures, either. Obtaining these types of disclosures should always be a part of your offer, and time is of the essence.