Why is no data available in the Contacts Tab in Smart URL?

Why is no data available in the Contacts Tab in Smart URL?

The visitors on your website might be just Anonymous visitors, which will not reflect any data in the contacts tab. Second, If known visitors do exist and visit the website, it cannot track the visitors and data will not be collected in the absence of a tracking code script in the website. Data will be tracked only if the script is applied to the website and will be available in the Contacts Tab of Smart URL.