The legal and social institution through which two or more parties create binding obligations by mutual agreement — the mechanism that organizes most of market society, that has been extended metaphorically to explain political obligation and social order, and that illuminates the conditions under which voluntary exchange is genuinely voluntary.
Every time you click 'I agree' without reading the terms, you sign a contract. Legally, you are bound. But you had no meaningful choice about whether to agree — the alternative was not using the service. This gap between the form of consent and its substance is not a modern problem. It has been at the center of contract law and contract theory for centuries. The question the contract raises is always the same: when is an agreement genuinely free, and when is 'I agree' simply what you say when you have no real alternative?