Any business rules that need to be changed easily later, that is almost anything and everything. Examples include discount rates, loyalty points, insurance premiums and so on. Especially when you have domain experts creating and updating the rules.

Take a look here at the drools (the java equivalent to nools) documentation: https://docs.jboss.org/drools/release/5.4.0.CR1/drools-exper...

The usual idea is (1) to encourage stronger separation between the actual business logic and any boilerplate that surrounds it and (2) to write business logic in a way more accessible to non-developers.

A rete-based rules engine is more than just a sequence of if-then statements, they allow for any rule to assert new facts that then cause other rules to trigger/retrigger. This also lets you gradually introduce new facts and have the results updated.