Content Identifiers (CIDs)
A content identifier is a value that addresses a single piece of content in IPFS. It is mainly a cryptographic hash of the content, but is encoded as a multihash and multicodec. (Note: older CIDs have a different design — see version 0 below.)
Version 1 is the latest version of CID. It is used by default for
files (MFS) and
When IPFS was first designed, we used base 58-encoded multihashes as the content identifiers. (This is simpler, but much less flexible than newer CIDs.) It is still used by default when adding files and blocks to IPFS, so you should generally try to support them.
The CID specification includes a decoding algorithm you can use to distinguish CID v0 from newer versions.