The first look in RTB (Real-Time Bidding) refers to the initial opportunity for an advertiser to bid on and win an ad impression in a real-time auction. This occurs when a user visits a website or app, triggering an ad request that is then sent to an ad exchange. Advertisers then have a split second to evaluate the user’s profile and bid on the impression, with the highest bidder winning the opportunity to display their ad to the user. The first look is crucial in RTB as it sets the tone for the entire bidding process and can greatly impact the success of an ad campaign.