First look is a term used in the context of online advertising to refer to the exclusive access that some advertisers or ad networks have to inventory, or ad space, on a particular website or app. First look means that these advertisers or ad networks have the ability to purchase ad impressions on the website or app before they are made available to other advertisers. This can give these advertisers an advantage, as they have the opportunity to reach their target audience before their competitors do. First look can also be beneficial for publishers, as it can help to maximize the value of their inventory and to attract high-quality advertisers. However, first look arrangements can also be controversial, as they can potentially limit competition and reduce transparency in the advertising market.