Agreement

Agreement as a part of contract includes offer and acceptance. Acceptance is an expression of unqualified agreement to all the terms set out in the offer. An offer is an expression of willingness to contract on a specific set of terms. The importance is those sets of terms let both sides plan. An offer may be withdrawn at any time before it is accepted.

Does silence mean acceptance? Generally silence is not acceptance and the offeror cannot impose the offeree to speak. But there are exceptions: 1) the offeror says nothing 2) the parties mutually agree that silence means acceptance 3) in previous dealings the parties considered silence to be acceptance.

e.g. A man wants to rent conference room in a hotel for an event. He calls to the hotel and asking if there is available room on needed date, are meals included etc. When he has finally chosen the date and room this fact allows him and the hotel manager plan. He can think over what to buy for a lunch, how many guests to invite and so on. Hotel manager will book the room for him so other clients will know that exact room on exact date is not available.

Consideration

Consideration is the concept of legal value in connection with contracts. It is anything of value promised to give to another when making a contract. It can be money, physical objects, services, promised actions and much more. It is based on QUID PRO QUO (something for something). The mutual promises must be real but not illusory. A promise to do what somebody already agreed to do or carry moral obligation is not consideration. Moreover, the importance is that consideration makes you privy to the contract and privity lets you sue. But no one who is not within the contact can sue parties.

e.g. A young couple decided to marry and their fathers agreed to give them exact sum of money monthly. But, unfortunately, father of the lady died and angry fiancé wanted to sue. It could not be so because according to the law, as I already mentioned, no one who is not within the contract can sue parties.