Language & WorldHow it works
You sign contracts every day without signing anything.
A contract forms through offer and acceptance: the baker offers the roll, you take it and pay, done. Written form is the exception, required by law only for certain deals such as buying land or, in many countries, guarantees. A signature mostly serves as proof, not as a condition of validity. Even a promise sent by chat can be binding.
Useful: Before you type "sure, I'll do it", remember that may already be a binding contract.
Source: en.wikipedia.org