Keep me logged in until I sign out. Minors and the mentally incompetent lack the legal capacity to enter into contracts. All others are generally assumed to have full power to bind themselves by entering into contracts. In most states, the legal age for entering into contracts is 18. The test for mental capacity is whether the party understood the nature and consequences of the transaction in question.
Corporations have the power to enter into contracts.
They make contracts through the acts of their agents, officers, and employees. Whether a particular employee has the power to bind the corporation to a contract is determined by an area of law called agency law or corporate law. If you doubt whether an individual with whom you are dealing has authority to enter into a contract with you, insist that the contract be reviewed and signed by the corporation's president. A corporation has a separate legal existence from its founders, officers, and employees. Generally, the individuals associated with a corporation are not themselves responsible for the corporation's debts or liabilities, including liability for breach of contract.