As a buyer, you have to enter into a sale agreement or contract with the seller of the real property. This requires three essential requisites to make the sale agreement valid and binding:

1. consent of the contracting parties
2. object certain which is the subject matter of the contract
3. cause or consideration of the obligation which is established

Consent of the contracting parties is manifested when you agree to buy the X property of the seller and pay the agreed price and the seller agrees to deliver the X property (not the Y or Z property) to you upon receipt of the purchase price.

However, consent given by (a) unemancipated minor or those persons below 18 years old; or (b) insane or demented persons or deaf-mutes who do not know how to write makes the contract void (Art. 1327, New Civil Code). If the consent is given through mistake, violence, intimidation, undue influence or fraud, the contract will be voidable or valid until annulled (Art. 1330 NCC).