Display network
A display network is the vast collection of third-party websites, apps, and videos where an ad platform can place your visual banner and image ads, Google's being the largest, reaching most of the web. Unlike search ads, which appear when someone actively looks for something, display ads appear as people browse content elsewhere, so they're about creating awareness and staying visible rather than capturing active demand.
For a founder, the display network is the engine behind retargeting and broad brand-building campaigns. Its strength is cheap, wide reach: you can put your brand in front of huge audiences for a fraction of search costs. Its weakness is intent, these viewers aren't looking for you, so click and conversion rates are low and it's easy to waste budget on irrelevant placements. The disciplined use is tight targeting (retargeting warm visitors, or carefully chosen audiences and placements) rather than spraying ads everywhere. Treat display as a support channel for awareness and re-engagement, not a primary demand-capture play.