Facebook has enabled view-through attribution by default for newly created campaigns using web events, which they say is beneficial for many industries including eCommerce and Retail. The idea is that this will provide an understanding of the types of users who may see an ad on Facebook and later make a conversion, without clicking on the ad. View through attribution provides additional context on user action based on ad exposure over a longer time frame, and this expansion will provide more capacity to track ad response. Learn more here.