1. Offer. An offer may be oral or written as long as it is not required to be written by law. This is the defined phrase or manifest action that begins the contract. It's simply what is offered to another person for the return of that person's promise to act. This can not be ambiguous or unclear. It must be specified in specific terms and some, such as the identity and nature of the object offered and under what conditions and / or conditions it is proposed.
2. Acceptance. As a general legal proposal, it is the acceptance of the offer made by one party by the other party that constitutes the contract. As a general rule, this acceptance can not be withdrawn, nor modify the conditions of the offer, nor modify or modify it. Doing this makes acceptance a counter-offer. Although this proposal may vary from state to state, the general rule is that there is no conditional acceptance by law. In fact, by making a conditional acceptance, the recipient refuses the offer. However, the bidder, at his option, by an act or word that shows the acceptance of the counter-offer, may be bound by the terms offered by the recipient.
Consideration. The consideration for a contract may be money or another right, interest or benefit, or loss, loss or responsibility assigned to another person. Consideration is an absolutely necessary part of a contract. As a warning, it should be noted that both parties to the contract must expressly agree on the consideration or that it must be expressly implied in the terms of the contract. A potential or accidental benefit or injury alone would not be interpreted as a valid consideration. The consideration must be explicit and sufficient to support the promise to do or not to do, regardless of the situation. However, it does not need to have a particular monetary value. Mutual promises are an adequate and valid consideration for each party as long as they are binding. This rule also applies to conditional promises. As a further clarification, the general rule is that the promise to act that you are already legally required to make does not constitute sufficient consideration for a contract. The courts determine the claim
4. Capacity of the parties to contract. The general presumption of the law is that everyone has the ability to contract. A person who tries to avoid a contract should plead his incapacity to contract against the party trying to enforce the contract. For example, he should prove that he was a minor, declared incompetent, drunk or drugged, and so on. This is often the most difficult burden of proof to overcome because of the presumption of ability to contract.
5. Intention of the parties to the contract. The formation of any contract, whether oral or written, implies that the parties agree on mutual consent or "consensus" on all proposed terms and all essential elements of the contract. The courts have held that there can only be a contract if all the parties involved have the intention of concluding it. This intention is determined by the external actions or actual words of the parties and not only by their intentions or secret desires. Therefore, mere negotiations to reach mutual agreement or contract approval would not be considered an offer and an acceptance even if the parties agreed on some of the conditions being negotiated. Both parties must have intended to conclude the contract and one can not have been misled by the other. This is why fraud or certain errors can make a contract voidable.
6. Object of the contract. A contract is not enforceable if its object is considered illegal or contrary to public policy. In many jurisdictions, contracts based on lotteries, dog racing, horse racing or other forms of gambling would be considered illegal contracts. Yet in some states these types of contracts are valid. Federal and state laws make contracts restrictive of trade, pricing and illegal monopolies. Therefore, a contract that violates these laws would be illegal and unenforceable. This is true for drugs and prostitution or any other activity if it is considered criminal.