A visit is recorded when a user accesses your website URL and a PageView, PixelInitialized, or ViewContent event is fired by the pixel. The Facebook pixel must be installed on the webpage. Every time someone accesses your website through any channel, a new visit is counted and is either categorized as paid, organic, or direct.
Only one visit will be recorded if the same URL is loaded more than once within 30 minutes of the previous visit. This only applies to sponsored clicks from ads whose destination URLs contain the UTM source and campaign. One visit would be recorded, for instance, if someone clicked on your advertisement, returned, and then clicked it once again.