It's annoying when a cyberattack knocks a bunch of high-profile websites offline, but it's mostly that — annoying. It's a bigger problem if an attack does physical damage.
The United States power grid is really important. Officials warn without it, a lot of society would grind to a messy halt. It's not just rhetoric, either. Lights, heat, air traffic control, hospitals — they all need electricity.
And it's a favorite target for hackers. The power grid suffers more cyberattacks than any other piece of American infrastructure.
But so far, we've only seen one cyberattack that did physical harm to a power grid, and it wasn't here. In 2015, digital attackers knocked parts of Ukraine's power system offline.
That said, the U.S. isn't defenseless. Homeland Security has whole cyberwarfare teams just for protecting the grid and other industrial targets. They share info with the power industry.