Hi Lawrence, Relevant means that the thing is somehow significant in relation to the other. Irrelevant is the opposite: it can still be related to the other thing, but it has very little significance to it. When something is related to another, it means they have some level of relevance between, but how much is not defined. -- "I think it's highly relevant to ask if you have a driver's license, when you're applying to be a bus driver". "Having a driver's license is related to your capability to become a bus driver". "Age does not have much relevance in how we choose our drivers. We hire people both young and old." "Age is related to whether you're still legally allowed to drive. Also, we do not hire pensioners."