The short story is the product of print culture but is finding new ways to thrive in the internet era. This can be through print stories going viral online or, more experimentally, born-digital stories reconfiguring relationships between author, text, and reader. This chapter considers two main subcategories of born-digital short fiction. Microfictions are self-contained flash fictions predicated on absolute verbal economy. Commonly found on Twitter, they call on longer print histories of microfictional experimentation and the francophone journalistic tradition of faits-divers. The second subcategory, microserializations, drip-feeds a narrative across multiple tweets, as in Jennifer Egan’s “Black Box.” Here too the subgenre recalls earlier traditions of nineteenth-century periodical serialization and Japanese cellphone novels (keitai shosetsu). Microserializations thus reintroduce the concept of temporality into the consumption of fiction, reviving readerly anticipation and creator–audience interactivity. Digital culture thus provides exciting new horizons for the always mobile, innately transmedial short story genre.