https://arstechnica.com/gadgets/2020/02/lets-encrypt-issued-its-billionth-certificate-today/

Let's Encrypt, the Internet Security Research Group's free certificate signing authority, issued its first certificate a little over four years ago. Today, it issued its billionth.

The ISRG's goal for Let's Encrypt is to bring the Web up to a 100% encryption rate. When Let's Encrypt launched in 2015, the idea was pretty outré—at that time, a bit more than a third of all Web traffic was encrypted, with the rest being plain text HTTP. There were significant barriers to HTTPS adoption—for one thing, it cost money. But more importantly, it cost a significant amount of time and human effort, both of which are in limited supply.