Paid search is often the first channel new marketers are handed, because it looks simple: pick some keywords, write some ads, set a budget. It is simple to start. It’s also easy to waste money on if you don’t understand the machinery underneath.
The good news is that the machinery is logical. By the end of this piece you’ll understand what happens in the fraction of a second between someone typing a search and an ad appearing.
Why search ads are different
Most advertising interrupts people: a TV ad before a programme, a post in a social feed. Search ads don’t. They answer a question the person has just asked. Someone typing “best air purifier for small bedroom” is telling you exactly what they want, right now.
That’s the superpower of search: intent. It’s also its limit. Search can only capture demand that already exists. If nobody is searching for your product yet, search ads can’t create that interest; other channels have to.
▸ Definition — Search intent: what the person searching is trying to do: learn something, compare options, find a specific site or buy.
Keywords and match types
You don’t bid on searches directly. You bid on keywords, and Google decides which searches are close enough to trigger them. How close is set by the match type:
| Match type | Written as | Shows for | Example keyword → search it could match |
|---|---|---|---|
| Broad | air purifier | Searches related in meaning, even loosely | “air cleaner for allergies” |
| Phrase | “air purifier” | Searches that include the meaning of the phrase | “best air purifier for bedroom” |
| Exact | [air purifier] | Searches with the same meaning | “air purifiers” |
Broad match reaches the most people and gives Google the most freedom. Exact gives you the most control. Most well-run accounts use a mix, together with negative keywords: words you tell Google never to show for, such as “free”, “jobs” or “repair” if you only sell new units.
▸ Margin note — Match types have loosened over the years, so “exact” no longer means letter-for-letter. Always check the search terms report, the list of real searches that triggered your ads. It’s where you find new keywords and new negatives.
The auction
Every time someone searches, Google runs an auction among all the advertisers whose keywords match. But it isn’t won by whoever bids the most.
Think of it like a shop window on the busiest street in town. The landlord wants rent, but she also wants passers-by to keep coming to her street. So she gives the best window to the shop that pays well and that people actually want to visit. A shop that pays a lot but looks dreary gets a worse spot, or none at all.
Google’s version of that judgement is called Ad Rank. In simple terms it combines:
- Your bid: the most you’re willing to pay for a click.
- Quality: how relevant and useful your ad and landing page are likely to be for this search.
- Context: the device, location, time and the search itself.
- Ad assets: extra information such as sitelinks or prices that make the ad more useful.
The highest Ad Rank gets the top spot. And because quality counts, a more relevant advertiser can beat a higher bidder, and often pays less per click.
▸ Definition — Cost per click (CPC): what you actually pay when someone clicks. You pay only when someone clicks, not when the ad is shown, and usually less than your maximum bid.
Quality Score: the report card
Google gives each keyword a Quality Score from 1 to 10 as a diagnostic. It’s based on three things:
- Expected click-through rate: how likely people are to click your ad for this keyword.
- Ad relevance: how closely the ad matches what the person searched.
- Landing page experience: whether the page delivers what the ad promised, loads fast and works on a phone.
Quality Score itself isn’t used in the auction. It’s a summary that helps you see where you’re weak. A low score usually points to a mismatch: a keyword that’s too broad, an ad that’s too generic or a landing page that talks about something else.
▸ Example — A mismatch, fixed. Keyword: “air purifier for small bedroom”. Weak: an ad saying “Shop home appliances” that sends people to the homepage. Strong: an ad saying “Quiet air purifiers for small bedrooms” that sends people to a page filtered to compact, quiet models. Same bid, better quality, likely a lower cost per click.
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Principles
- 1Search captures existing demand; it doesn’t create it.
- 2Keywords are instructions, and the search terms report shows what Google actually did with them.
- 3Relevance lowers costs: match keyword, ad and landing page closely.
- 4The highest bid doesn’t automatically win.
Questions to ask on Monday
- When did we last look at the search terms report and add negatives?
- Which of our keywords have the lowest Quality Score, and why?
- Do our ads send people to the most relevant page, or to the homepage?
Paid search rewards patience and curiosity more than cleverness. If you check the search terms report every week, you’ll already be ahead of many accounts.