Zohran Mamdani declared victory in New York City’s Democratic mayoral primary Tuesday night after Andrew Cuomo conceded the race in a stunning upset. Mamdani is a progressive upstart who was virtually unknown when the contest began built a substantial lead over the more experienced but scandal-scarred former governor.

The term has no singular definition. But simply put, it’s an ideology rooted in its opposition to capitalism and wanting to shift power from corporations to workers.