How Are SEO, Paid Search, and SEM Related?

SEO focuses on attracting traffic through unpaid organic search results; paid search uses ads to appear in search results. Under the broad definition used in Yoast’s June 2026 article, SEM (search engine marketing) covers both organic and paid search, so SEO and search advertising both fall under SEM. PPC, meanwhile, refers to a pricing model in which advertisers pay for ad clicks, so it should not be treated as a category at the same level as SEO and SEM.

SEM is the umbrella term; SEO and search advertising are different approaches

To understand these terms, first ask: are we discussing search marketing as a whole, ways to gain visibility, or how ads are charged? Under the broad usage described above, the terms fit together as follows:

• SEM: Marketing efforts aimed at appearing in search results, including organic results and ads.
• SEO: Improving a website so it can appear when users search for relevant topics, with a focus on attracting organic search traffic.
• SEA: Buying search ads so they appear in search results for relevant keywords.
• PPC: Advertisers pay each time an ad is clicked; this is a pricing model used for search ads.

Under this definition, then, “doing SEM” does not mean just buying ads. However, this is the scope of the term used in this article; it does not establish that SEM means exactly the same thing in every article or service package.

Organic results and ads offer different routes to visibility

For example, suppose a website wants to be found in searches related to its products. Improving the website so that relevant pages appear in organic results is SEO; paying for search ads targeting relevant keywords is SEA. If the ads are charged on a per-click basis, that is PPC.

This example also shows that “unpaid search results” describes the source of traffic, while PPC describes how advertising costs are incurred. Keeping the two distinct makes it possible to discuss clearly whether the work involves improving organic search performance or buying search ads, rather than grouping everything under “increasing search visibility.”

SEO and PPC can complement each other, but that does not mean they deliver the same results

Yoast notes that paid results may place a website at the top of the results for a particular search term, but under a PPC model, each user click through to the site incurs a cost. “May appear at the top” is not a ranking guarantee, nor can it be interpreted as a guarantee of sales.

The same source considers SEO and PPC to have their own advantages and disadvantages and says they can often complement each other. They therefore need not be treated as mutually exclusive options: they address organic results and ad visibility, respectively. However, this general observation is not enough to determine each website’s budget allocation, nor does it establish that either approach will necessarily deliver better results.