Integrated search glossary

Search engine marketing (SEM)

Search engine marketing (SEM) is the practice of winning visibility on search engine results pages, most often through paid ads bought in an auction on platforms such as Google Ads and Microsoft Advertising. Some marketers also include SEO in the term, so agree a definition before comparing budgets or agencies.

Reviewed by Gareth Hoyle, Managing Director
Last reviewed 31 October 2026

Does SEM include SEO?

It depends who is speaking. In older usage SEM was an umbrella for everything done to gain search visibility, paid and organic. Today most marketers use it to mean paid search, with SEO treated as a separate discipline. The two share the same results page, the same searchers and the same keyword data, which is why many businesses plan them together.

How does paid search work?

Advertisers choose keywords, write ads and set bids. Each time someone searches, Google runs an auction that weighs the bid against the quality of the ad and landing page, and the advertiser usually pays when the ad is clicked.

Google launched AdWords on 23 October 2000. It announced on 27 June 2018 that AdWords would become Google Ads, and the new brand began appearing on 24 July 2018.

How SEM and SEO work together

Paid search buys visibility immediately and stops when spending stops. Organic visibility takes longer to build and keeps working. In 2011 Google reported that, across more than 400 studies where advertisers paused their search ads, 89% of the paid clicks lost were not replaced by organic clicks. That figure is an average and comes from Google, so it is worth testing against an account's own data.

Use paid search terms data to find converting queries worth targeting organically
Use organic rankings to decide where paid spend adds least
Test ad copy quickly, then use winning messages in page titles

Example

A new online tile retailer runs Google Ads from launch to get sales while its category pages are too new to rank. Six months later, the search terms report shows 'outdoor porcelain tiles' converts well, so the business builds a dedicated category page for it and watches whether paid spend on that query can fall as organic rankings rise.