A more thorough explanation:

Definition: Self-executing broadly refers to something that goes into effect or can be enforced after being created without anything else required. Often self-executing refers to a clause of a contract or law that makes the document effective after the document is signed or other requirement. Self-executing is to be contrasted with documents, legislation, or rights that require other steps in order to be enforced.

Examples:

• A self-executing contract is one that becomes effective as soon as it is signed by both parties.
• A self-executing law is one that goes into effect as soon as it is passed by the legislature.

These examples illustrate the definition of self-executing by showing how a contract or law can be enforced without any additional steps. In both cases, once the document is signed or passed, it becomes effective without any further action needed.