When the Age Verification add-on is enabled in a store, any not-logged-in customer will need to pass the age verification to access the store content.
Depending on the display mode configured for the pop-up, a visitor will be suggested to confirm the age with a button or to specify the age manually to access the store content.
Two-button display mode
Text verification display mode
The underage visitors will not be allowed to access the site and will see a respective message with a suggestion to leave the site.
All customers that pass the age verification limit will gain access to the site content.
The age verification form completely relies on the visitors' trustworthiness and can not 100% prevent underage visitors from viewing the store content in case of deception.