I may be referring to Massachusetts law. IANAL. Contracts require consideration[1]. If we agree you will give me $400 tomorrow, that is not a contact. If we

I may be referring to Massachusetts law. IANAL. Contracts require consideration[1]. If we agree you will give me $400 tomorrow, that is not a contact. If we agree that I will give you $200 today and you will give me $400 tomorrow, that is a contract.[2] [1] http://en.wikipedia.org/wiki/Consideration http://en.wikipedia.org/wiki/Consideration [2] There are other components that make contracts legal; technically I'm only describing the consideration aspect.