This article explains how to pin websites in Safari and macOS, and how to remove a pinned website from the tab bar. This information applies to macOS 10.11 and Safari 9 and later.
How to Pin Tabs in Safari Mac OS X – Apple Training
OS X El Capitan introduced several improvements to Safari, including the ability to pin your favorite websites. Pinning places the site's icon in the upper-left corner of the tab bar, making it accessible with a single click. Websites you pin in Safari are live; the page refreshes continuously in the background.
Site pinning only works on the tab bar. Follow these steps to make it visible and pin a website to it:
If you don't see the tab bar, go to the View menu and select Show Tab Bar.
