Rules Engine
martinfowler.com/bliki/RulesEngine.html
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
A rules engine is all about providing an alternative computational model. Instead of the usual imperative model, commands in sequence with conditionals and loops, it provides a list of production rules. Each rule has a condition and an action - simplistically you can think of it as a bunch of if-then statements.