By default on Safari, Mac users can view link previews in separate windows to take a peek at the website they're about to visit without clicking through. This can be handy for checking headlines or other content before deciding if a link is worth visiting, but the feature has never reliably worked on my Mac. It's supposed to trigger on a force-click or three-finger click on the trackpad, but both inputs can be finicky enough that I tend not to use link previews at all. That changed recently thanks to app developer Jeff Johnson, who discovered a keyboard shortcut Apple has never disclosed that reliably triggers Safari link previews while on Mac.
The Safari link preview keyboard shortcut
When you're using Safari on your Mac, hover the mouse pointer over any link and press Command-Control-D. A link preview should pop up for you every time. It's still a bit wonky, because you can't easily dismiss this link preview by pressing the Esc key on your Mac's keyboard, but you can click anywhere outside the preview to dismiss it.
With this shortcut, I no longer have to open links in a background tab in Safari for later viewing. Also, it makes it much easier to open link previews while using an external mouse, where force-clicking and three-finger-taps aren't an option. You can also use it on individual words to pull up Look Up, which shows the definition of the word, in addition to an array of other search results about it.
Note that Link Preview works as intended in Safari for iPhone, where you can press and hold any link to see a quick preview.
Before previewing any link, it's important to remember that you should practice the same safety precautions you would when opening a link, since a preview will still load all of a page's content, including images and code.
Incidentally, Johnson is the developer of the excellent StopTheMadness Safari extension, which makes web browsing a lot better. The extension stops autoplaying ads on websites, removes tracking information from URLs, alerts you when you've exceeded the character limit while making passwords for certain websites, and can re-enable copying and pasting on websites that block it.