Still images on the internet come primarily in three formats: JPEG, GIF or PNG. If you want transparency, then PNG is king (having long dethroned the ancient GIF). In sad news, one of the co-creators and maintainer of the format, Glenn Randers-Pehrson, passed away last week from "a long and painful illness".
The world was informed on his passing via a message on SourceForge from Magic Leap engineer and current PNG maintainer Cosmin Truta:
I am deeply saddened to inform you that Glenn Randers-Pehrson, our long-time group lead, passed away last weekend, following a long and painful illness.
Truta goes on to mention Randers-Pehrson's 20-year stewardship of "libpng", or PNG Reference Library. This is essentially the core implementation of the PNG format, from which all other implementations are derived in some form or another, be it in Photoshop or your web browser.
Along with being the driving force behind the format, Randers-Pehrson holds the honour of the first person to ever post a PNG to the web, all the way back in March 1995. Unfortunately, the so-called "paleo" images are no longer available.
RIP Glenn, and thanks for everything you did for the web and computer graphics.