SEA: the guide to paid search

What is SEA (paid search)?

SEA stands for Search Engine Advertising: advertising on search engines. It is also called paid search, or sponsored links. The ads appear above or below the organic results, with a label that marks them as advertising.

On Google, ads go through Google Ads, Google’s advertising platform. On Bing, through Microsoft Advertising. The principle is the same: the advertiser targets queries, sets a budget and most often pays per click (CPC).

SEA has three strengths. It is visible as soon as it goes live. It can be managed day by day. It can be measured click by click. Its limit is the mirror image: traffic stops when the budget stops. In Google Ads, an account is structured into campaigns, ad groups and ads.

Google Ads auction: who shows up and at what price?

For every search, Google runs an auction between the eligible ads. The result is Ad Rank. It is recalculated for each position on the page (Google Ads Help on Ad Rank). Google lists six factors:

• the bid amount, meaning the most you are willing to pay for a click;
• the quality of the ad and of the landing page;
• the minimum thresholds required to show;
• the competitiveness of the auction against other advertisers;
• the context of the search: terms, location, device, time;
• the expected impact of ad assets (sitelinks, location, phone number).

The direct consequence: a more relevant ad can rank ahead of a competitor that bids higher. SEA rewards quality, not just budget. The full path, from query to billed click, is described in how Google Ads works.

How much do you really pay for a click?

You do not pay your maximum bid. The actual CPC is the final amount charged for a click. According to Google, it is often lower, sometimes much lower, than the maximum CPC. It covers what is needed to beat the ad ranked just below and to meet the thresholds (Google Ads Help on actual CPC).

Quality Score, a diagnostic tool

Quality Score rates each keyword from 1 to 10. It rests on three components: expected clickthrough rate, ad relevance and landing page experience.

Google states that it is not used in the auction. It is a diagnostic indicator, calculated by comparison with other advertisers (Google Ads Help on Quality Score). So you do not optimize it for its own sake: it shows you where to look. A component-by-component reading is on our Quality Score page.

Which campaign types for SEA?

Google Ads offers several campaign types. Each one matches an inventory and a goal (Google Ads Help on campaign types):

Type	Where the ads show	Typical use
Search	Google search results	Capture expressed demand
Performance Max	All Google Ads inventory from a single campaign	Sales or leads with clear conversion goals
Shopping	Product listings in the results	E-commerce with a product feed
Display	Partner websites and apps	Awareness, remarketing
Video	YouTube and partner sites	Awareness, consideration
App	Several Google networks	Installs and in-app actions

Performance Max serves ads from a single campaign across YouTube, Display, Search, Discover, Gmail and Maps. Google recommends it to businesses with specific conversion goals (Google Ads Help on Performance Max). Its strengths and blind spots are detailed in our Performance Max guide.

For a first account, start with a Search campaign, limited to a few queries with strong purchase intent. It is the most readable starting point: you see which queries trigger your ads, what they cost and what they bring in. More automated campaigns come later, once conversion tracking is reliable and the history is sufficient.

To choose and structure your campaigns according to your goal, see Google Ads campaigns.

How do you choose keywords and write ads?

A keyword is not a query. The keyword is what you set up in Google Ads. The query is what the user actually types. The match type sets the gap allowed between the two (Google Ads Help on match types).

Match type	Syntax	Triggers the ad on
Broad match	tennis shoes	searches related to the keyword, in the broad sense
Phrase match	“tennis shoes”	searches that include the meaning of the keyword
Exact match	[tennis shoes]	searches with the same meaning or the same intent

Two habits limit waste:

• check the search terms report every week;
• exclude queries that cannot convert (jobs, free, definition, competitor brands depending on your policy) with negative keywords.

On the ad side, the headline echoes the intent of the query. The description gives a concrete reason to click. The landing page keeps the promise of the ad. This consistency is what the Quality Score components measure. The full method is in keywords and ads.

What does automated bidding (Smart Bidding) do?

Smart Bidding strategies use Google AI to optimize for conversions or conversion value in every auction. They take into account signals such as device, location, time, remarketing lists or the actual query (Google Ads Help on Smart Bidding).

Strategy	What it aims for	Practical prerequisite
Maximize conversions	The most conversions for the budget	Conversions tracked correctly
Target CPA	Conversions at a target cost per acquisition	Enough conversion history
Maximize conversion value	The highest value for the budget	A value assigned to each conversion
Target ROAS	A target return on ad spend	Reliable conversion values

Choosing a strategy, setting a realistic target, getting through the learning period: that is the subject of our Smart Bidding page.

How do you measure and optimize an SEA campaign?

Five metrics are enough to manage most accounts:

Metric	Calculation	What it tells you
CTR	clicks ÷ impressions	Does the ad match the query?
Average CPC	cost ÷ clicks	How much does attention cost?
Conversion rate	conversions ÷ clicks	Does the page keep the promise?
CPA	cost ÷ conversions	How much does a customer or a lead cost?
ROAS	conversion value ÷ cost	Does each euro invested bring in more than one euro?

These metrics only make sense if the conversion is well defined: a qualified quote request, a purchase, a booked appointment. In lead generation, feed the leads that became customers back into Google Ads if possible. Otherwise, the account optimizes forms, not revenue.

A simple routine is enough to start:

• every week: search terms and negative keywords;
• every month: ads, landing pages, budget allocation;
• every quarter: account structure and conversion goals.

A rule of caution: wait for enough conversions for the difference to be readable before judging a change. On a small account, a few sales are enough to double or halve the CPA. For account audits and optimization levers, see the Google Ads audit.

What budget should you plan for an SEA campaign?

There is no standard budget. The cost depends on the price of clicks in your industry, the search volume and your conversion rate. The calculation works backwards, from what a customer brings you.

1. Set the acceptable CPA: the margin on a sale, or the value of a lead multiplied by the closing rate.
2. Estimate the CPC: with the Google Ads Keyword Planner, on your priority queries.
3. Estimate the conversion rate: your site’s rate on qualified visitors, or a cautious assumption.
4. Calculate the test budget: enough clicks to get a readable number of conversions over four to eight weeks.

Fictional example: a CPC of €2, a conversion rate of 4%. A conversion then costs €50 on average (2 ÷ 0.04). If a customer brings you €40 in margin, the campaign loses money on every sale. Improve the page or target more qualified queries before increasing the budget.

SEA or SEO: do you have to choose?

No, and the best results often come from combining them. SEA quickly tests an offer, a message or a query. SEO builds lasting visibility on the queries that have proven themselves. The data from one feeds the other.

Criterion	SEA	SEO
Time to visibility	As soon as the ads are approved	Several months in general
Cost	Paid for each click	Upfront work, clicks not billed
Stopping	Traffic stops with the budget	Traffic holds as long as the page stays relevant
Management	Day by day, keyword by keyword	Slower, less predictable

Brand queries, data sharing, budget trade-offs: these cases are developed in SEO and SEA together. For the organic lever, see our SEO guide.