Embedded link by pressing the Insert/Edit link button?

In a post I highlighted the text for another post’s url and then pressed the “insert/edit link” button to make that text hyperlinked and, instead of doing what it usually does by just making the text a different color to show hyperlinked status, it added a small clickable featured image, the post title and a brief description, which is great but I didn’t know how I did it and can’t seem to recreate it.

I now understand that this is an embedded post but I do not have the oEmbed plugin.

If this is some function new to 4.4 then how do I embed a post other than accidentally( which is what I did)?