Over the past year, the world’s leading browsers have added features enabling web applications and publications to “phase shift” between online and offline states. Surrounding these new features is a growing set of communities broadly coalescing around the term “offline-first.” In this talk, we’ll take a look at some of the key bits of technology being used by these new phase-shifting applications, as well as how the W3C’s Digital Publishing Interest Group is exploring these (and other ideas) for possible use in Portable Web Publications. March 23, 2017