A 'Rule' is a computer instruction that sets up the what a software application will do next.
A rule is very often of the form
"IF this condition is true THEN do this OR ELSE do this"
For example an expert system might have a rule that says: "If person has red spots then she might have measles'.
Or an online shopping cart application might have been programmed to react when a rule is met
"If the customer has hesitated for more than 10 seconds in filling in their order details, then pop up a help screen"
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Rule