I had explain about few of the essentials of a valid contract in the previous blog please go through it once and read that first and after reading the previous blog you can continue understanding these further points. The father essentials of a valid contract are as follows: 

1. Lawful object: object usually refers to the objective of a goal or instead we can call it as a purpose of something we do similarly lawful object reports to the purpose of the agreement according to the legal obligations where the contract is considered as unlawful when it is forbidden by law or any fraudulent activities takes place if the contract maker on the acceptor is injured while making the contract then the contract cannot be considered as lawful.
2. Not expressly declared as void: IPC section 24 to 30 there are the list of void contracts which can be considered as unenforceable or which cannot be enforced by the law. As they are considered to be void.
3. Certainty and possibility of performance: which means that the contract should be certain and the possibility of performance should be sure and the terms and conditions of key agreement must be precisely mentioned as well as they must be capable of execution or else there won't be any certainty of possibility of performance of that contract which is made. Thanks by making the contract the terms rules are the conditions must be precisely mentioned and they must be in such a way that they are capable for executive and the surface little must exist in order to increase the possibility of performance.
4. Legal obligation: legal obligation is nothing but the enforceability by the law where the social or domestic agreement that is agreement between the family of the bonds cannot create the legal obligation only the agreements which are legally acceptable are considered as contract and they must abide to all the obligations as equal to the law aur the Indian contract act of 1872.
5. Legal formalities: legal formalities are nothing but a step-by-step procedures for the formal steps which must be satisfied in order to consider it as a valid contract. All the legal formalities must be met in the contract where all the above essentials of valid contract must be satisfied in the contract and the formalities must be satisfied.

Hence the part 1 and 2 of the essentials of valid contract gives you a detailed explanation about what are the points you must take into consideration in order to make valid contract according to the law