Updatable, human-readable usernames for accounts.
DIDs are the long-term persistent identifiers for accounts in ATproto, but they can be opaque and unfriendly for human use. Handles are a less-permanent identifier for accounts.
The overall handle must contain only ASCII characters, and can be at most 253 characters long.
Handles are domain names which are used to identify data repos. More than one handle may be assigned to a repo. Handles may be used in at:// URIs in the domain segment.