Time of contract establishment: Article 25 of the Contract Law stipulates that "a contract is established when the acceptance takes effect". The most basic legal effect of acceptance is that once the acceptance is made and delivered to the offeror, the contract is declared. In other words, when the acceptance comes into effect, it is also the time when the contract is legally established.
The conclusion of a contract means that both parties to the contract reach an agreement on the main terms of the contract on the basis of equality and voluntariness. Legally speaking, the conclusion of a contract can be divided into two stages: offer and acceptance. For example, A said to B, I will sell you my computer for 2000 yuan (offer), and B said it was a deal (commitment). Both parties have written a contract, which will take effect after it is signed and sealed. This is a simple contract.
Also: you go to the clothing store to buy clothes. The clothes on the hanger are all marked with prices. You took a fancy to a dress and offered to buy it at a price of 20%. The clerk agreed to your counter-offer and sold it to you. Here, the price tag behavior of the store belongs to the invitation to offer, your counter-offer belongs to the offer, and the consent of the salesperson belongs to the promise. This is a process of concluding an oral contract.