Search engine advertising: how Google Ads works and when it pays.

Paid search has an appealing promise. You switch on a campaign in the morning and by the afternoon your business sits above the organic results. That part is true. The catch is that every click costs money, including the clicks from people who land on your site and leave because the message is unclear or the page does not convert. Without a clear story, a working website and honest measurement, you mostly buy traffic.

This guide explains what search engine advertising is, how the Google Ads auction works, which campaign types exist in 2026 and how to calculate CPC, CPA and ROAS, including a formula for setting a target ROAS from your margin. Definitions come straight from Google Ads Help. It also covers when advertising is worth it, when to fix the foundation first and what to own if you hire an online advertising agency. At Viralistic we work organic first, and we run Google Ads once that foundation is healthy.

What is search engine advertising (SEA)?

Search engine advertising is paid advertising inside search engines. Your ad appears above or below the organic results, labelled as sponsored, when someone searches for a term that matches your offer. In practice SEA almost always means Google Ads. Microsoft Advertising, which serves ads on Bing, is the best-known alternative.

Google describes Google Ads as its online advertising programme for reaching people at the moment they are interested in the products and services you offer. There is no minimum spend: you set and control your own budget.

A few terms get mixed up, so here is how they relate:

• SEA (search engine advertising) is, strictly, ads in search results. It is the term used most in Europe.
• PPC (pay-per-click) is the pricing model behind most search ads, and in the US it is often used as a synonym for paid search.
• SEM (search engine marketing) is used in two ways. Some use it for paid search only, others as the umbrella for SEO and SEA together.
• Google Ads is the platform. It runs search ads, and also ads on YouTube, Gmail, Discover and sites in the Google Display Network.

Google Ads was called Google AdWords until 24 July 2018. It is the same platform under a newer name.

SEA vs SEO vs SEM: what is the difference?

SEO earns unpaid positions in the organic results. SEA buys paid positions around them. SEO compounds over time and keeps working when you pause, while SEA works immediately and disappears as soon as you stop paying.

Is PPC better than SEO? Neither wins on its own. They answer different questions. Search term data from your campaigns shows which words actually bring customers, and you can feed that into your content. In the other direction, a strong organic presence makes every paid click more effective, because people who research you find a consistent, authoritative brand. Our guide to SEO optimisation covers the organic side, and SEO vs GEO explains how AI answers change it.

How does the Google Ads auction work?

Google runs an auction every time someone searches. For each eligible ad it calculates an Ad Rank, which decides whether the ad shows and where. On search campaigns you usually pay only when someone clicks, and often less than your maximum bid.

What decides your Ad Rank

According to Google Ads Help on Ad Rank, the inputs include:

• your bid;
• the quality of your ad and landing page;
• Ad Rank thresholds;
• the competitiveness of the auction;
• the context of the search, such as location, device and time of day;
• the expected impact of assets, such as sitelinks, and other ad formats.

So the highest bid does not automatically win. Google states that even if competitors bid more, you can still win a higher position at a lower price with highly relevant keywords and ads.

Quality Score is a diagnostic, not a lever

Quality Score rates each keyword from 1 to 10. It combines three components: expected click-through rate, ad relevance and landing page experience. Each one is rated above average, average or below average, compared with other advertisers whose ads showed for the exact same search over the last 90 days.

Many explanations still describe Ad Rank as bid multiplied by Quality Score. Google says otherwise. Quality Score is not an input in the auction and not a KPI to optimise. It is a diagnostic tool that shows where your ad, keyword or landing page could improve. The underlying quality does count in the auction, and that is where the work is.

Bidding and budgets

You choose a bid strategy. With manual CPC bidding you set a maximum bid per click yourself. With Smart Bidding, Google sets a bid for each auction using signals such as device, location and time of day, aimed at a goal: maximise conversions, hit a target CPA, maximise conversion value or hit a target ROAS. From June 2026, Google Ads labels the goal-based versions simply as Target CPA and Target ROAS. The bidding behaviour stays the same.

You set an average daily budget. On a busy day Google can spend up to twice that amount, but over a month it never charges more than your average daily budget multiplied by 30.4.

Types of Google Ads campaigns

Google Ads offers several campaign types. Only Search campaigns are search engine advertising in the strict sense. The others show ads beyond the results page, or only there.

Examples of search engine advertising in the strict sense are a text ad that appears when someone searches “accountant Amsterdam”, or a Shopping listing with a product image and price for “linen sofa”.

What happened to Discovery ads

Discovery campaigns no longer exist as a separate type. Google replaced them with Demand Gen, and all remaining Discovery campaigns were upgraded automatically between January and March 2024, keeping their historical data.

Demand Gen campaigns combine image and video in one campaign and serve on YouTube, including Shorts, Discover, Gmail and the Google Display Network. They support audience options such as lookalike segments built from your own customer data. For campaigns using target CPA bidding, Google recommends a budget of at least ten times that target CPA.

Display is moving into Demand Gen

Google Display campaigns are being folded into Demand Gen, with the Google Display Network becoming one of its channels. Since June 2026, eligible advertisers can move existing campaigns voluntarily with a migration tool in their account. Later, new campaigns can only be created within Demand Gen and remaining eligible campaigns will be migrated automatically. If you are hiring someone for display advertising, ask how they are handling the move.

Which type should you start with?

For most service businesses and B2B companies, a Search campaign is the sensible starting point. You reach people at the moment they search, and you keep control over keywords, copy and landing pages. Performance Max and Demand Gen lean harder on Google’s AI and on your creative assets. Both need reliable conversion tracking, because that is the signal the system optimises towards.

CPC, CPA and ROAS, with worked examples

CPC is what you pay per click, CPA is what you pay per conversion, and ROAS is the revenue you get back for every unit of ad spend. You calculate all three from numbers Google Ads already reports: cost, clicks, conversions and conversion value.

With CPC bidding you set a maximum CPC. The actual cost per click is often lower than that maximum.

A worked example

Say an online skincare store spends EUR 3,000 on Google Ads in a month. That brings 2,000 clicks, 60 orders and EUR 12,000 in revenue, excluding VAT.

• CPC: EUR 3,000 ÷ 2,000 = EUR 1.50
• CPA: EUR 3,000 ÷ 60 = EUR 50
• ROAS: EUR 12,000 ÷ EUR 3,000 × 100% = 400%

A ROAS of 400% means every euro of ad spend returns EUR 4 in revenue. Google uses the same arithmetic in its Help article on Target ROAS: 5 in sales ÷ 1 in ad spend × 100% = a 500% target ROAS.

How to set a target ROAS from your margin

Revenue is not profit, so 400% means little until you know what is left after the cost of goods. Start with your break-even ROAS, the point where gross profit exactly covers ad spend. Then add the profit you want to keep.

• Break-even ROAS = 1 ÷ gross margin × 100%
• Target ROAS = 1 ÷ (gross margin - desired profit after ad spend) × 100%

Express both as a share of revenue, excluding VAT. With a gross margin of 50%:

• Break-even ROAS is 1 ÷ 0.50 = 2, so 200%. Below that, every sale loses money once ads are paid.
• If you want 20% of revenue left as profit after ad spend, ads can take at most 50% - 20% = 30% of revenue. Your target ROAS is 1 ÷ 0.30 = 3.33, so about 333%.

The store in the example runs at 400%, comfortably above target. EUR 12,000 in revenue leaves EUR 6,000 gross profit, and after EUR 3,000 in ad spend that is EUR 3,000, or 25% of revenue.

Two practical checks. Make sure the conversion value you send to Google Ads uses the same definition as your calculation, for example revenue excluding VAT and shipping. And account for returns, or your ROAS will look better than your bank balance. To use Target ROAS bidding on Search and Shopping campaigns, Google requires at least 15 conversions in the past 30 days, with values assigned to them.

Selling services? Work back to a target CPA

If customers arrive through an enquiry form or a call, there is no revenue in your ad account to calculate ROAS from. Work back to a maximum CPA instead:

Maximum CPA = gross profit per new client × share of leads that become clients

Say a new client is worth EUR 6,000 in gross profit on average and one in five leads becomes a client (20%). A lead is then worth EUR 1,200 before you earn nothing from it. If you want to keep half, your target CPA sits around EUR 600. For clients who stay for years, use the value of the relationship rather than the first project.

What is a good ROAS?

A good ROAS is one above your own target ROAS. There is no universal benchmark worth trusting, because the same 400% is profitable at one margin and loss-making at another. These factors decide what good looks like for you:

• The thinner your margin, the higher the ROAS you need.
• Whether conversion value includes VAT, shipping and returns changes the number.
• If customers come back, the first order can cost more.
• Campaigns on your own brand name often show a high ROAS because those people were already looking for you. Judge them separately from campaigns that have to find new customers.
• Are you optimising for profit right now, or for growth and new customers?
• Conversions sometimes arrive days after the click. Google advises leaving out the most recent conversion delay period when you evaluate ROAS, so do not judge a campaign on yesterday’s numbers.

Do not set the target too high either. Google notes that an overly ambitious target ROAS can limit the traffic your ads receive.

Is search engine advertising worth it?

Search engine advertising is worth it when people already search for what you offer, when the value of a customer can carry the click prices in your market and when your website turns visitors into enquiries or sales. If one of those is missing, you mostly pay for traffic.

Advantages and disadvantages

When it pays

• People already look for your product or service. Without volume, a Search campaign has little to catch.
• The numbers work: your target CPA or target ROAS is achievable at the click prices in your market. Keyword Planner in Google Ads gives an early indication of search volume and bids.
• You want to test something quickly, such as a new service, a new region or a seasonal peak.
• Your website converts and you can measure it. Without conversion tracking, Smart Bidding has nothing to steer on and you never learn what a customer costs.

When to fix the foundation first

When someone asks us for ads, we often say no and suggest a different first step. Three situations come up again and again:

• You cannot explain the value of your business within a few minutes. Campaigns will amplify the confusion. A brand script is the first step.
• Your website underperforms or cannot be found. You would pay to send people to a place that loses them. Fixing the page also helps your ads, since landing page experience is one of the three Quality Score components.
• Your SEO and visibility in AI answers are not in order. You will keep buying every visitor instead of earning them.

When every building block is in place, you usually already see enough results. If the foundation is healthy and you still need more clients, ads become the cherry on top. Read more about that order in our marketing approach, and about turning channels into one plan in our guide to digital strategy.

Choosing an online advertising agency

Hire the craft, but keep the account, the billing and the measurement in your own hands. A good digital advertising agency works in your account through its own user or manager account, while the account itself stays with your company. The same rules apply whether you outsource Google Ads, display or a wider mix of digital marketing and advertising.

What you should own

• The Google Ads account, in your company’s name and with your own payment method. You then pay media spend directly to Google, and your campaign history stays yours.
• Admin access. Only admins can grant access, change access levels and unlink manager accounts. Google recommends at least two admins: with only one, you can lose access to your tags if that person becomes unavailable.
• Ownership. Agencies work from a manager account. If an agency creates a new account from its manager account, that manager becomes the owner automatically. If you link an existing account, it does not get ownership by default. As Google Ads Help on client account ownership explains, the client account remains the owner of its data and can remove an owner by unlinking it. So create the account yourself and invite your partner in.
• Your measurement: the Google tag, your conversion actions and your Google Analytics property, all in your company’s name.
• Your copy, images and landing pages. Agree in writing who holds the rights.

What a good agency shows you

• Reporting tied to your business: cost per lead or ROAS against your margin, not only clicks and impressions.
• A clear split between the management fee and the media budget.
• Search term transparency: which searches actually triggered your ads, and which were excluded.
• A test plan: what gets tested in the first months, and when you decide together.
• Attention for the landing page, not only the ad.
• No lock-in: you can leave without losing your account or your data.

In the first call, also ask who works on your account day to day, and how they handle Performance Max and the move from Display to Demand Gen. And notice whether they ask about your brand and your customers. Ads that sound and look like your brand identity start from a clear story, not from a keyword list.

How we help

Viralistic is a strategic digital partner in Amsterdam, founded and led by Marrallisa Kreijkes. Our marketing is organic first. Before a single euro goes to ads, we check the foundation. Can you explain the value of your business in a few minutes? Does your communication say the same thing everywhere? Does your website work, and are you found in Google and recommended in AI answers? Whatever is missing, we fix first, in the right order: story, website, findability.

When the foundation is healthy and you still need more clients, we run Google Ads and Meta Ads. We take the communication basis from your brand script and build the campaigns off your brand guide, so every ad sounds and looks like you. We experiment first on a larger audience, review the results with you and then decide together where to focus more budget. You see every number and you help decide the next move. Read more about our marketing approach and SEO & AIO.

Frequently asked questions

Is PPC better than SEO?

Neither is better on its own, because they do different jobs. PPC buys visibility immediately and is ideal for testing offers and covering peaks, but it stops when the budget stops. SEO builds rankings that keep bringing visitors without paying per click. Most businesses get the best results with a strong organic foundation first and paid search on top once that foundation converts.

What are some examples of search engine advertising?

A text ad above the results when someone searches “family lawyer Amsterdam” is search engine advertising. So is a Shopping listing showing a product photo, price and store name for “leather weekend bag”. Both appear because the search matches keywords or products the advertiser chose, and both carry a sponsored label. Ads on YouTube or in Gmail run through Google Ads too, but they are not search ads.

How much does search engine advertising cost?

You decide. Google Ads has no minimum spend: you set an average daily budget, and over a month you are never charged more than that daily budget multiplied by 30.4. What you actually need depends on click prices in your market and on the target CPA your numbers allow. If you hire an agency, its management fee comes on top of the media budget.

What happened to Google Discovery ads?

Google replaced Discovery ads with Demand Gen campaigns. Any remaining Discovery campaigns were upgraded automatically between January and March 2024, with their historical data intact. Demand Gen combines image and video ads in one campaign and serves them on YouTube, including Shorts, Discover, Gmail and the Google Display Network, with audience options such as lookalike segments.

What does CPA mean in advertising?

CPA stands for cost per acquisition, also called cost per action. It is what you pay on average for one conversion, such as a purchase, a lead form or a sign-up. Divide your ad spend by the number of conversions to get it. In Google Ads, the Target CPA bid strategy lets you set the average cost per conversion you want to pay.

What does a digital advertising agency do?

A digital advertising agency plans, builds and manages paid campaigns on platforms such as Google Ads and Meta. That includes keyword and audience research, ad copy and creative, bidding, conversion tracking and reporting. A good one also challenges the landing page and the offer, works in an account you own and reports in business terms such as cost per lead or ROAS against your margin.