What is https://i1.wp.com/ … ?ss1

Hi,

I manually added an a href to images in the code editor to an image in a wordpress site’s media and text block and the images are opening at the url — https://i1.wp.com/%5Bactual image url]?ssl=1 — and with a Jetpack icon in the tab instead of my website’s icon.

Can you please explain what is happening and why?!?

Thank you for your support.