The 2016 election brought the so-called “alt-right”—the loose collection of individuals and groups with aggressive right-wing and far-right political identities who reject the bounds of mainstream conservatism—to the forefront of American politics. From conspiracy-minded media pundits to sexist Internet trolls and white supremacists, this toxic crew has been emboldened by Trump’s presidency. Who are they, what are the roots of their politics, and how can we demolish their noxious ideas? Katie Feyh investigates.