When marketing campaigns are targeted to users that live in a certain zip code. For example, a restaurant promotion might target customers that live in the restaurant's zip code.
One of the key hurdles in doing zip code marketing is generating a lead list with zipcode information for each customer. This can be sourced via site sign-up, customer loyalty programs, or hiring an agency that specializes in finding this data.
See "IP Targeting". https://www.thanx.com/zip-code-marketing/