Pre-roll is a type of online advertising that is shown before the main content on a website or app. Pre-roll ads are typically short video ads that are played before a video or other piece of content, and that are designed to grab the user's attention and to deliver the advertiser's message. Pre-roll ads can be an effective way for advertisers to reach and engage with their target audience, and to drive brand awareness and engagement. Pre-roll ads can also be beneficial for publishers and platforms, as they can provide a new source of revenue and a valuable source of content and engagement for their audience. However, pre-roll ads can also be disruptive and annoying for users, and can lead to a negative user experience if they are not implemented in a responsible and transparent way.