Contract, agreement, or document? All of the above!

Sometimes, clients come to me to beef up informal arrangements they have made for business ventures.  Often the parties are friends, and my client doesn't want to scare his or her friend/business partner with a lengthy legal document.  A client will sometimes request "just something showing our agreement, not a formal contract."  The truth is though, these terms are interchangeable.  No matter how it is titled, a contract will be enforceable if it is made between two parties, for valuable consideration (usually money, or the promise to act or refrain from doing a particular action), and accepted by both parties, where both parties are competent and have the capacity to enter into an agreement.  While I haven't had the opportunity to review any agreements scrawled on napkins lately, the medium and method of the agreement don't matter too much -- emails, napkin contracts, and "formal" contracts can all be enforceable if they have the requisite elements of a binding contract.