Remember when Biden was campaigning and he said if elected he would enact a national mask mandate? At the time I scoffed noting the President doesn't have the power to do that. Well, he's released details about the mask mandate. Biden has said he'll be working with governors and mayors to enact mask mandates. As a Vox article said, it's not as much a mask mandate as a mask suggestion.
For the record, I think people should be wearing masks in public but it is such a difficult thing to mandate. Public education and working with businesses to require masks on their property would likely be far more effective.