In one sentence

A business rule is a stable statement of how a particular decision should be made.

The simple model

A business rule connects a condition to an outcome:

IF a customer is in the public sector
THEN payment terms are 30 days

The key word is stable. A real business rule should give the same answer every time the same conditions apply. That is what makes it a rule rather than a judgment.

Why you care

Business rules are the parts of a workflow that usually belong in deterministic automation, not in an AI model. They are easy to test, easy to explain and cheap to run.

Separating the rules from the interpretation is one of the most useful things you can do before designing an AI workflow. It shows you which parts need a model and which parts do not.

Rules hide inside habits

People often state rules as habits: "I always check the customer type first." Behind that habit is a rule about what the customer type changes. Part of understanding a workflow is turning these habits into explicit rules that everyone agrees on.

Watch for rules with exceptions

Many rules are almost stable. "All orders over the limit need approval, except from these three trusted accounts." The exception is part of the rule. Write it down, or the rule will seem to fail whenever the exception appears.

A small example

A support team escalates tickets. The rule turns out to be: "Escalate if the customer is on the premium plan and the issue is unresolved after four hours, unless it is a known outage." Three conditions and one exception. Once written like this, it can be automated reliably and checked by anyone.

What this does not solve

A clear rule can still be wrong or out of date. Rules need an owner who updates them when the business changes, the same as any other piece of knowledge.