NFTs can be hard to grasp. What the heck is a non-fungible token? While most of the world grapples with understanding what they are or how they work, one company has taken the lead as the most successful NFT marketplace in the world. How did OpenSea, a company now valued at over $13B — billion! — become the defacto marketplace for buying and selling NFTs? The Verge’s Russell Brandom explains.