Back in 2012 WordPress removed the “Links” menu from the admin dashboard. This menu still exists on the Commons. In order to use it, you needed to add links through the Links menu, then go over to Appearance/Widgets and activate the Links widget on your sidebar. This is pretty convoluted, and the same functionality can be created by creating a custom menu of custom links (there’s a Custom Menu widget that will display any menu you build, including menus full of custom links that point to other websites).
As WordPress adopts the Customize functionality more and more to avail a simple way to build how your site looks, holding onto functionality like the links menu creates a disconnect that I’m hoping to rectify (you can build a custom menu in the customizer, but you can’t leverage the old links menu). I think we held onto the Links functionality for too long. I don’t know of anyone who is using it, and it adds an additional menu item in the admin panel that seems superfluous now.
All of that to say that I’m deactivating the links functionality today. If you were using it, you can re-activate it on your own site by going into the Plugins menu on your site and Activating the “Links Manager” plugin. If you would like help migrating over to a custom menu, here’s a quick video: