PDFs were one of the most important implementations on the web. The cool thing about them is that they can be streamed out as they’re being built and then wrapped up at the end.
At one time I had read the entire PDF spec from cover to cover and can still navigate the text versions of PDFs.
PDF is amazingly simple and graceful in its design.
Well, it's a shame he had to die for me to find out what PDF stood for.
RIP John Warnock