All legal documents have different requirements in order to be considered legal in the eyes of a court.
For example, a contract requires mutual acceptance by both parties along with something of value (called “consideration”) that is exchanged between them. Without something of value being exchanged, many agreements aren’t enforceable by law.
This is different from something like a cease and desist letter or a last will and testament, which have a different set of legal requirements but are also enforceable in a court of law.
When creating your legal documents, be sure that you’re aware of what kind of document you intend to create, and ensure that it is signed and witnessed appropriately for full legal consideration.