Consideration in a contract must provide some benefit, detriment, or responsibility to be valid. It can be an act, promise, forbearance, or abstinence done at the desire of the promisor. Consideration needs to be real rather than illusory and cannot be something the promisor is already legally obligated to do. As a general rule, only parties to a contract can sue upon it due to privity of contract, however there are exceptions such as assignments, trusts, or contracts made through an agent.