Three distinct roles, one directional flow
Decentralized identity systems are built around three clearly separated roles. The issuer is the party with the authority or standing to make a claim, a university confirming a degree, a licensing board confirming a credential, a government confirming an age. The holder is the subject of that claim, the person or entity the credential is about, who receives the signed credential from the issuer and keeps it in their own possession, typically in something like a digital wallet. The verifier is whoever later needs to check the claim before granting access to something, like a bar checking age or an employer checking a license.
The flow between them runs in one direction and only needs to happen once per credential: the issuer signs a claim and gives it to the holder. From that point forward, the holder is the one who presents the credential wherever it's needed, and it's the holder, not the issuer, who initiates every subsequent interaction. This is a deliberate design choice, it puts the holder in control of when and to whom their credentials are shown, rather than requiring the issuer to be an active participant in every downstream use of a claim it made once.