Over the past few weeks, social media controversies around election meddling, fake news, and censorship have put tech platforms on the hot seat. Three of the biggest platforms involved — Facebook, Twitter and YouTube — have all slowly introduced changes to their policies in response to pressure, mostly from lawmakers, as well as users and advertisers.

Regulators say that the tech companies are doing better to combat homegrown extremism, but that more needs to be done.

Why it matters: These companies all have business models centered around scale, and are not incentivized to apply more scrutiny to the content or ads on their platforms unless pushed to do so by outside forces. It's the beginning of a wave of backlash against big tech in Washington and beyond for failing to police the content on its platforms for years.