Stored, and sometimes run, directly on a blockchain rather than linked from an outside server. An on-chain artwork keeps its code or image in the chain's own data, so it survives as long as the chain does.
Then I do think working with blockchains was quite important because it gave collectors a way to engage with the software directly, especially with the on-chain work.
Dmitri Cherniak, Dmitri Cherniak on Strictly for Art