Are you referring to a contract for work done or service performed, such as when a website designer does work for a client?
If so, be aware that, in most jurisdications, a contract will be deemed to exist, even if it's not expressly stated in writing. So, if you say to your client: "I can do your website for X", and he replies: "Fine, go ahead", then that's your contract.
It's really no different from going into a shop and saying "I want to buy a can of beans" and the guy behind the counter saying "Here you are". A contract will automically exist for the purchase of the beans.
Of course, in these cases, you are not setting out any specific terms for contract, other than perhaps the price and the general scope of the work. So, if it came to a dispute, you would have to rely on what a reasonable person would expect the terms to be for a contract of that type. If, for example, it's normal in your country for the client to be given all intellectual property rights for a website they commission, then they will have that right, unless you specifically agree otherwise.
I'm not saying yo can get by without a written contract. I'm just saying that you can't argue that no contract exists, just because it's not in writing.