# Custom **Domain:** Social Order / Law / Governance **Doc Type:** Concept Node **Maturity:** Developed ## Definition **Custom** is a practice sustained through repetition, inheritance and mutual expectation before, or alongside, formal legislation. It is not merely frequent behavior. A practice becomes customary when participants treat it as an intelligible pattern that carries some claim on future conduct. Custom is broader than [[wiki/Social Norm|social norm]] and less formal than law. A convention may solve a coordination problem; etiquette regulates ordinary interaction; ritual stabilizes meaning and transition; a social norm adds approval or sanction. Custom can contain all of these while remaining historically embedded and only partly articulated. ## Historical Lineage Customary orders precede many states and remain active within them. Trade usage, common-law reasoning, local tenure, professional practice and administrative routine often begin as repeated arrangements before institutions recognize, codify or reject them. Formalization does not erase the underlying custom: written rules frequently depend on inherited expectations for interpretation and compliance. ## Governing Variable Custom governs expectation. It marks which actions appear normal, permitted, obligatory, rude, deviant or unintelligible before an official decision is made. ## Material and Computational Manifestation Custom appears in greetings, queues, routes, workplace routines, household practices and the tacit use of shared space. Computational systems have analogous inherited defaults: protocol conventions, file layouts, interface idioms and configuration assumptions can constrain later development without having been selected by one continuing authority. The analogy is structural, not historical proof that custom is software. [[wiki/Custom as Proto-Code|Custom as Proto-Code]] is the corpus synthesis that develops this limited correspondence. ## Constitutional Question and Failure Modes Custom can preserve local knowledge that centralized rules cannot see. It can also naturalize exclusion, conceal coercion and burden outsiders who cannot discover an unwritten rule. The constitutional question is when inherited practice deserves deference and when public reasons, rights or appeal must displace it. ## Related Ontology [[wiki/Social Norm|Social Norm]] · [[wiki/Informal Enforcement|Informal Enforcement]] · [[wiki/Custom as Proto-Code|Custom as Proto-Code]] · [[wiki/Law as Spatial Logic|Law as Spatial Logic]]