We primarily make use of browser cookies to store information about customer interactions with our zip code validator. If you check your store cookies, you would see following cookies in there.
rbz-customer-closed-popup: This would indicate whether customer has closed a pop-up validator.
rbz-zipcode: This would indicate customer entered zip code. If customer isn't validated yet, this cookie wouldn't exists.
rbz-is-serviceable-zipcode: This would indicate whether customer lives within serviceable are or not.
Based on these cookie values, you can implement variety of things on your end based on your need. We've seen some merchants going above and beyond and customizing entire validation flow. Note that we don't provide support for making these customizations as this involves modifying your theme code and add some additional helpers depending on your requirements.
Use case #1 : https://getblooming.com/