An ad that is “relevant” to me is an ad that leads me to think “yes, this item is exactly what I was looking for”. Sometimes you know you want to buy something (let’s say a backpack) but you don’t know which brand/model to go for.

This is where ads come in: a backpack company can run ads that should be shown to people interested in buying backpacks, and it’s potentially a win-win: you find a cool item that you buy, and the company gets a new customer.