Left-foot braking is most often associated with rallying and high-performance track driving. It allows the driver to modulate the brakes without removing their right foot from the throttle pedal, improving reaction time. But as Wyatt Knox from the explains, left-foot braking can be useful on the road too.
Like in racing, it all comes down to reaction time. If you brake with your right foot, as most people do, you have to lift your foot off the throttle and move it to the brake pedal before anything happens. That takes time. If you instead keep your left foot hovering over the brake pedal, you don't have to waste that time transferring your right foot from one pedal to the other. It only saves a fraction of a second, but that could be the difference you need in a panic-stop situation.
Knox is quick to point out you shouldn't just have your left foot hovering over the brake pedal at all times—that would be pretty uncomfortable just cruising down the highway. Instead, he suggests using the practice in high-risk driving situations (fog, dirt roads, back roads at night where wild animals can appear).
And if you're feeling a little intimated by left-foot braking (the sensation of using your clutch foot to brake can be jarring), Knox also put together a quick video explaining an easy way to approach the method. With some practice, you'll be left-foot braking through corners in no time.