How do GoogleAds work?

Factual Questions
1

A little background: when I scrolled down to the bottom of this thread, about pickles, I noticed a GoogleAd:

Preserving Garlic
Preserving Garlic reviews And 100s more consumer topics
www.Which.co.uk

Having what may be an excessive interest in pickled and marinaded garlic, I clicked on the ad. Which took me to a Which? page which was effectively an index of garden-related reviews that can be accessed (presumably) for money.

No complaints about the fact that Which? want me to pay to access their reviews. That’s their prerogative. And presumably, if you pay your money and you clicked down, somewhere you’ll find something about preserving garlic - which might mean pickling or marinading it, or it might just be ‘how best to store your garlic bulbs’.

So now for the questions:

Firstly, why did Google decide to link that page to a pickle thread?
Secondly, why did they (or Which?, who are paying for the GoogleAds service) make the ad link to a not immediately relevant page?

Having had a certain passing acquaintance with SEM/ SEO, I know that GoogleAds and the algorithms that Google use generally are shrouded in a veil of secrecy. But I’d still appreciate any pointers.

<whine>
Dammit, I clicked cause I wanted a fail-safe recipe for pickling garlic so I would have stocks to see me through the winter.
</whine>

2

Does this help?

(I have to admit, the first one looks interesting: “Combine all ingredients in … your dishwasher.” :eek:

3

I’m no expert, but since no one else has addressed your questions: When you (or, in this case, Which) create a Google ad, you specify the keywords that you want. I believe Google then puts that ad on pages that have some of your chosen keywords. So, in this case, Which probably had “pickle” or “pickled” among the keywords, so the automated Google ad-placer thought the ad belonged on a page about pickles. As to why Which linked their ad to that page, only they know the answer to that one. But it was Which, and not Google, that decided what to link the ad to.