The law of contract in the Western world states that, for a contract to be enforceable, it must be underpinned by consideration. 
Can a contract be enforced without it?
Consideration is the value exchanged between the parties to a contract for the contract.
Some examples:
I buy your car for $5000. $5000 is the consideration.
You agree to rent my house for $200 per week. The money is the consideration.
Bob agrees to babysit for a three week period for $45 per night. The money is the consideration.
Farmer Brown agrees to graze his neighbours sheep in return for the neighbour topping his trees. Consideration obviously flows between the two men.
Throughout the 17th Century and the first part of the 18th Century, consideration was regarded by the Courts as an integral part of a contract. Courts struggled to enforce contracts which has "no consideration" but which were obviously moral contracts.
Any New Zealand textbook on Contract Law will contain a Chapter on Consideration. All law students study it carefully starting with its original origins centuries ago and the attack on the concept by a famous British Judge, Lord Mansfield 150 years ago.
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