Which of the following best describes display ads?

Display ads are best defined as advertisements that are visually presented separately from the main content of the webpage. They typically appear in defined spaces on a website, such as banners, sidebars, or pop-ups, making them distinct from the text or media that make up the primary content of the site. This separation is crucial as it allows advertisers to capture the user's attention without blending in with the surrounding material, often leading to higher visibility and click-through rates.

When considering the other potential descriptions, contrast helps clarify the definition. Ads that exclusively appear on social media (the first option) do not encompass the broader realm of display advertising, which can exist on various websites beyond social platforms. Ads that are integrated seamlessly into online content (the second option) refer more to native advertising, where the ads align closely with the site's format and appearance. Lastly, limiting ads to mobile applications (the fourth option) excludes many other places where display ads can be found, as they are prevalent on both desktop and mobile web environments. Thus, defining display ads as those presented separately from the primary content accurately captures their nature and function in digital marketing.