What is SEA? Search advertising explained

The difference to search engine optimisation in one line: SEO is living rent-free after a long build, SEA is renting with immediate occupancy. You pay per click, and in exchange you are visible tomorrow.

How the ad auction works

The highest bid does not simply win. Every search triggers an auction in which two things meet: your bid and the quality of your ad.

Google summarises that quality in the Quality Score, which draws on three things: expected click-through rate, how well the ad matches the search, and the experience on the landing page. Bid and quality together produce the ad rank.

In practice: a well-built ad with a matching landing page pays less per click than a poor ad with a high bid. Ignore the landing page and you pay the difference.

You also do not pay your own bid, but roughly what it takes to beat the next competitor. A maximum bid therefore says little about actual cost.

The main ad formats

• Search ads. Text above the organic results. The core, because this is where someone is actively looking.
• Shopping ads. Product images with prices, relevant for online retail.
• Performance Max. An automated campaign type covering all Google surfaces. Convenient, but hard to see into – rarely the first choice on small budgets.
• Display and YouTube. Image and video inventory across Google’s network. This is no longer search advertising but reach, and should be judged accordingly.
• Bing Ads. Smaller reach, often cheaper clicks, surprisingly effective in some B2B niches.

Beyond Google and Bing, ads can also be booked on social networks, on Pinterest, on Reddit, in audio streaming and, since August 2026, in ChatGPT. The overview is on Where can you run digital ads.

What a click costs

There is no universal figure. The price depends on how many competitors bid on the same search and how much a deal is worth in your field.

The rule of thumb that helps: do not think in click prices, calculate backwards. What is an enquiry worth to you? How many enquiries become clients? How many clicks does one enquiry take? Only then can you say which click price is bearable. Without that calculation, any click price might be the wrong one.

When SEA pays off

• Where intent is clear: someone searching for an emergency dentist wants one now, not next month.
• When you want to test quickly which message lands, before writing it into an entire website.
• For time-boxed occasions: an opening, a season, an event.
• When nothing organic exists yet and the first enquiries cannot wait.
• To defend searches for your own brand name when competitors bid on it.

When it does not

• When the landing page does not convince. Paid traffic to a weak page is a machine for turning money into bounces.
• When the margin cannot carry click prices. On cheap products with thin margins the maths stops working fast.
• When the budget is so small that the campaign never gathers enough data to improve. Below a certain threshold you pay tuition without learning.
• When nobody manages it. Ads do not get better on their own, they get worse on their own.

Four mistakes that reliably cost money

No measurement. Without conversion tracking you know how many clicks you bought, not what came of them. The most expensive gap of all.

Everything in one campaign. Throw search terms with entirely different intent into one ad group and you get an ad that fits none of them properly.

No negative keywords. Without them you pay for “free”, “training”, “reviews” and “jobs” as well.

Sending traffic to the homepage. Someone searching for a service should land on that service, not in the lobby.

SEA, SEO and consent

Two things that often get overlooked. First: ads and search engine optimisation do not compete, they feed each other. The terms that demonstrably produce enquiries in ads are the best candidates for content that will later carry organically. Conversely, SEA can bridge the time until SEO works.

Second: without working consent management you lose measurement data – precisely the data used to steer the campaign. Tracking and consent belong in place before the first ad runs.

Frequently asked questions