Preroll refers to a type of online video advertisement that plays before the main content. It is commonly used in video streaming platforms and websites.

These ads typically have a fixed duration and are played automatically when a user initiates the video playback. Preroll ads are designed to capture the viewer's attention and deliver the marketing message effectively.

Preroll ads can be skippable or non-skippable, depending on the platform and ad settings. Skippable prerolls allow users to skip the ad after a few seconds, while non-skippable prerolls require viewers to watch the entire ad.

Advertisers often utilize preroll ads to reach a targeted audience and increase brand awareness. They can be an effective way to monetize video content and generate revenue for content creators or publishers.