How to Turn on Frequently Visited Sites on an iPhone

Open your iPhone's Settings. It's the app showing gray gears that can be found on the Home Screen.

Scroll down and tap Safari. It's about halfway down the page.

Slide the "Frequently Visited Sites" button to the On position. It will turn green. The button is listed under the "General" heading. Now, when you browse Safari, the websites you visit most often will be listed under the search bar when you type.