Hosain Rahman

For a 13-year-old company built on slickly designed Bluetooth headsets, the last two years have been nothing short of a revolution — both for Rahman and Jawbone. In 2011 he unveiled the Jambox rubberized wireless speaker, shaped like a rectangular prism, and it quickly became the top seller in its category. Later that year Rahman released the UP, a wristband computer roughly the size and weight of a Livestrong bracelet that could track an astonishing range of its wearers’ activities, even waking them during their optimal sleep cycle. Many units broke after a few weeks, but Rahman’s deft response — an open letter admitting there was a problem and allowing any owner to return the UP for a full refund — was hailed across Silicon Valley and beyond. (See feature story on Rahman at fortune.com.) A retooled UP will be released “soon,” Rahman says, and hey, it could be as big a hit as the Jawbone. Most hated jargon: Bandwidth. –R.B.