What is IPFS?
Also called: InterPlanetary File System
IPFS is a content-addressed storage network where files are retrieved by a hash of their contents. The hash changes if the data changes, so references are tamper-evident.
In practice
Content addressing proves the file you fetched is the file that was referenced, but it does not guarantee anyone is still hosting it. Data stays available only while some node pins it, which is why NFT metadata can quietly break. Pinning services and Filecoin exist to make persistence someone’s explicit job.