These are blockchain-based platforms that let users trade in NFTs. OpenSea, Rarible, and Nifty Gateway are examples that you may have heard of, and many of them tend to use Ethereum or Solana.
As mentioned elsewhere, users will be able to join the creator economy by producing virtual items that people can buy. They could be anything from unique pieces of clothing to make avatars look more exclusive to dances. This may sound like an odd thing to buy until you realize that dances are one of the most popular features in the online multiplayer survival game Fortnite.
It’s a truism that although we are social creatures, we love to differentiate ourselves from others, and that desire is something that can always be monetized. The new economies that spring up around serving these needs will be key to making the metaverse viable in the long term.