A contract is nothing more then an agreement between two parties. Verbal agreement is a contract but one that is put in print and signed by all parties involved is easier to look at and determine what was originally agreed upon. Still you can have one that is fairly simple with little details and end up in litigation when one party doesn't get what they thought they were supposed to get. Or you can have one with a lot of details that spells out not only what products or services will be included but when where and how they will be implemented, as well as one that clearly spells out how progress payments will work during the contract, how unforeseen situations are to be handled, deadlines for when certain aspects will be completed, what time a space is available, or even who cleans up any mess at the end of the day, the list of possibilities that may be covered is unlimited.