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SEO vs SEM: What's the difference?

SEO and SEM strategies help marketers put digital content in front of the right audience. However, SEO strategies focus on organic search whereas SEM generates paid traffic.

As many people search the internet on a regular basis, marketers turn to SEO and SEM strategies to increase their content's visibility on search engines.

Search engine optimization (SEO) and search engine marketing (SEM) techniques both offer organizations ways to increase sales, but they use different approaches. Over time, SEO strategies can help organizations boost their organic search ranking, whereas SEM strategies harness paid advertisements to quickly increase site traffic.

To ensure marketing teams focus on the right strategy for their business needs, they should understand key differences between SEO and SEM, such as the search results they target, the time they take to bear results and their short- and long-term costs.

What is SEO?

SEO is the process of improving a website to increase its organic -- or unpaid -- visibility on major search engines. Companies like Google and Bing use algorithms to ensure their search engines show relevant, high-quality search results for queries, so marketers use SEO strategies to ensure these algorithms favorably rank their content. The goal of SEO is to organically rank on the first page of a search engine results page (SERP) for a specific keyword or phrase.

What is SEM?

SEM is the use of paid advertisements to increase search engine visibility. SERPs on Google and other search engines contain two types of content: organic results and paid advertisements. On Google, paid ads often appear at the top, side or bottom of a SERP. Organizations can pay to have their webpages appear in these highly visible locations.

3 key differences between SEO and SEM

Although SEO and SEM both help organizations generate web traffic, marketers should know their key differences, such as the types of search results they target, the amount of time they take to offer results and their overall costs.

1. SEO and SEM target different search results

SEO and SEM have the same overarching goal: to increase an organization's visibility on search engines. However, they each focus on different ways to achieve that goal. SEO focuses on the creation and enhancement of webpages to improve their rankings in organic search results. SEM focuses on the use of paid advertisements to rank at the top of SERPs.

To help pages rank organically, marketers use SEO best practices to create content that search engine algorithms tend to favor. Although companies like Google and Bing don't publicly disclose every detail about how they rank pages, the algorithms evaluate dozens of criteria, which include the following:

  • Title tags. A page's title should contain the content's main keyword -- or at least a variation of it.
  • Content quality. Marketers should create well-written, thorough and well-organized content.
  • Mobile friendliness. As more people conduct searches from their mobile devices, search engines prioritize sites that fit in mobile browsers.
  • Websites with many backlinks -- links from external websites -- tend to rank high on SERPs.
  • Site speed. Search engine companies don't want to send users to slow pages, so their algorithms prioritize sites that load quickly.

As part of an SEO strategy, marketing teams may use the above criteria to guide them as they create digital content. These SEO best practices can help creative teams eventually reach the first page or first position on Google for their content's keyword or phrase without paying for those top spots.

On the other hand, with SEM, marketers use paid ads to automatically appear at the top of SERPs for keywords and phrases that relate to their content. Two key types of SEM advertising on Google are search ads and shopping ads.

Search ads. Organizations can bid on a keyword or phrase, so a link to their page automatically appears on SERPs for that term. These ads follow a pay-per-click (PPC) model in which users pay a fee for every time someone clicks on the ad.

A screenshot of a Google SERP that highlights where paid search ads appear on Google
Google search ads let marketers pay to have their sites appear at the top, bottom or side of the SERP for a given keyword.

Shopping ads. These ads also follow a PPC model, but they use Google Shopping to link to an organization's e-commerce product page. These ads include an image of the product, along with the product title and price.

A screenshot of paid shopping ads on a Google SERP
Marketers can invest in Google shopping ads which, unlike search ads, display product photos and link to e-commerce pages.

As people query search engines for keywords and products, they may see ads for relevant pages and products. SEM ads offer marketers a quick way to get their brands, content and products in front of their target audiences.

2. SEO takes longer to deliver results than SEM

SEO takes more time to deliver results than SEM. An SEO strategy can take anywhere from three months to two years to offer significant ranking improvements, whereas an SEM campaign can increase an organization's web traffic within hours.

As millions of people use search engines to find products and services they want, the digital marketing industry has become highly competitive. To reach the top of the SERP's organic results, organizations should build a comprehensive library of high-quality content, accrue backlinks from external sites and ensure a positive UX for visitors -- all of which takes time.

SEM, on the other hand, can generate traffic immediately after marketing teams launch a campaign on a platform like Google Ads. Before a campaign launch, marketers must research their target audience and craft high-quality landing pages for their ads, which can take some time. However, once teams have these landing pages in place, the SEM campaign can immediately bring in paid traffic.

3. SEO costs more than SEM in the short-term

SEO doesn't cost money in the way that SEM ads cost per engagement, but to achieve organic visibility, organizations must invest a lot of time and effort into SEO. Organizations that want to improve their SEO may need to hire content writers and SEO strategists or invest in SEO tools. Because results can take months or years to offer an ROI, SEO has a high upfront cost.

On the other hand, once an organization achieves organic visibility, it can receive lots of traffic for no charge, which makes SEO highly profitable in the long run. With SEM, marketing teams can see instant results. However, when the marketing budget runs out, the organization's visibility drops to where it was before the campaign launch.

Should marketers use SEO or SEM?

For most organizations, an effective marketing strategy could focus on both SEO and SEM because the two processes complement each other. For instance, SEO best practices can help marketers create effective landing pages for their SEM campaigns. Similarly, new sites can use SEM campaigns to generate traffic, which can help them gain backlinks and improve SEO.

In some cases, an organization may only want to use one of these strategies. For example, organizations with a limited marketing budget may want to focus strictly on SEO until their budget increases. On the other hand, marketing teams that need quick results or lack the resources to create optimized content may focus on SEM. However, once organizations can supplement their SEO strategies with SEM, they typically do.

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