The monetary consideration for the goods sold is called price. If goods are exchanged for goods, it is only barter and not a sale.

(i) Contingent goods are the goods, the acquisition of which by the seller depends upon a contingency.
(ii) Contingent goods are a part of future goods.

(i)  Goods are materials that satisfy human wants and provide utility.
(ii) The term 'goods' includes every kind of movable property, stocks, and shares, growing crops, etc. Goodwill, trademarks, copy rights, patent rights etc., are all also regarded as goods.

Contract of sale of goods is a contract whereby the seller transfers or agrees to transfer the property (Ownership) of the goods to the buyer for a price.

In every contract of sale, there are certain expressed and implied conditions and
warranties.
The term implied conditions means conditions which can be inferred fromn or guessed from the context of the contract.

Following are the implied conditions :
(i) Conditions as to Title.
(ii) Conditions as to Description.
(iii) Sale by Sample.
(iv) Conditions as to Quality or Fitness.
(v) Conditions as to Merchantability
(vi) Condition as to Wholesomeness.
(vii) Condition implied by Trade Usage.
Following are the implied warranties :
(i) Quiet Possession.
(ii) Free from Any Encumbrances.
(iii) Warranty in the case of Dangerous Goods.

Existing goods are those owned or possessed by the seller at the time of contract of sale. Goods possessed even refer to sale by agents or by pledgers. The existing goods may be either :
(i) Specific Goods : Specific goods denote goods identified and agreed upon at the time of contract of sale.
(ii) Ascertained Goods: The term 'ascertained goods' is also used as similar in meaning to specific goods.
(iii) Unascertained or Generic Goods: These are goods which are not identified and agreed upon at the time of contract of sale.

The property (ownership or title) in the goods has to pass at a future time or after the fulfillment of certain conditions specified in the contract is called agreement to sell.

SI.No	Basis of Difference	Conditions	Warranty
1.	Meaning	It is a stipulation which is essential to the main purpose of the contract of sale.	It is a stipulation which is collateral to the main purpose of contract.
2.	Significance	Condition is so essential to the contract that the breaking of which cancels out the contract.	It is of subsidiary or inferior character. The violation of warranty will not revoke the contract.
3.	Transfer of ownership	Ownership on goods cannot be transferred without fulfilling the conditions.	Ownership on goods can be transferred on the buyer without fulfilling the warranty.
4.	Remedy	In case of breach of contract, the affected party can cancel the contract and claim damages.	In the case of breach of warranty, the affected party cannot cancel the contract but can claim damages only.
5.	Treatment	Breach of condition may be treated as breach of warranty.	Breach of warranty cannot be treated as breach of condition.

(1) Existing Goods
(i) Specific Goods - Specific goods denote goods identified and agreed upon at the time of contract of sale.
(ii) Ascertained Goods - (a) The term ascertained goods is also used as similar in meaning to specific goods.
(b) But this term may even refer to goods which become ascertained subsequent to the formation of the contract.
(iii) Unascertained or Generic Goods - These are goods which are not identified and agreed upon at the time of contract of sale.
(2) Future Goods
These are goods which a seller does not possess at the time of contract of sale but which will be manufactured or produced or acquired by him after entering into the contract of sale agreement
(3) Contingent Goods
Contingent goods are the goods, the acquisition of which by the seller depends upon a contingency (an event which may or may not happen). Contingent goods are a part of future goods.

SI. No	Particulars	Sale	Agreement to Sell
1.	Ownership Transference	The property(ownership or title) in the goods passes from the seller to the buyer immediately so that seller is no more owner.	The property(ownership or title) in the goods has to pass at a future time or after the fulfilment of certain conditions specified in the contract.
2.	Risk of Loss	Where the goods sold under the contract of sale are destroyed, the loss falls squarely on the buyer as the ownership in the goods has already passed on to the latter. Even though the goods are in the possession of seller.	Where the goods under the agreement to sell are destroyed, the loss falls squarely on the seller as the ownership is still vested with the seller even though the possession of the goods is with the buyer.
3.	Consequences of violating the contract	Where the buyer fails to pay the price, the seller cannot seize the goods. The seller can only file a case against the buyer for violating the contract.	Where the buyer. violates, the contract, the seller can repossess the goods from the former. He can sue for damages for violation of the contract.
4.	Nature of contract	It is an executed contract i.e. completed contract.	It is an executory contract, i.e. contract ye to be performed by the party to the contract.