kreemoweet said:
Because visiting a single website can actually generate web requests to many, many different web addresses, sometimes in the hundreds.
Your browser is downloading ads, trackers, javascript files, images, text, fonts, and all kinds of stuff from different locations.
It all goes in your history, and web cache if that's enabled.

And it doesn't stop either, after the initial page load. The page can keep requesting stuff behind the scenes constantly as long as you
navigate around on the webpage, and even just doing nothing with the webpage loaded.
Real comforting. Not.