Let's talk about non-fungible tokens (NFTs).
ERC-1155 can manage fungible and non-fungible tokens together in the same contract, and is often used for things like in-game items.
Honestly, I hadn't noticed this before: pay attention to what you're authorizing before listing on an NFT marketplace. Approving an entire collection at once lets the other party transfer all the NFTs in that collection.
Minting and buying or selling NFTs on Ethereum requires $ETH to pay gas fees.
Markets are always uncertain, so decide in advance what you'll do if your judgment turns out to be wrong.