Profile is the collection of publicly visible information associated with an hm://z6MkhfkiqVYBJ8krLBWPE1si6L9ugsbfswNReRL4fixvcVzS/definitions/account, such as name, avatar, and anything that might be relevant.

It's a state-based (snapshot) resource, to support quick and easy retrieval of this information, which is important, because it's the entry point to the Account's "public image".

The profile is the public and descriptive aspect of an account, whereas the account itself is the technical access and the overarching "control" structure.

Key Linking

We also use Profile blobs for identity redirects (aka key linking). When you link the key you created on the web to a key you have in your desktop app, the web key's Profile points the alias field of its Profile blob to the desktop's key. For this to work, there must be a hm://z6MkhfkiqVYBJ8krLBWPE1si6L9ugsbfswNReRL4fixvcVzS/definitions/capability with an AGENT role from Desktop to Web.

Profiles are Optional

We didn't have profiles before. We've been using the metadata on the site's home document to represent people. We keep using that as a fallback when we see an account and can't find its Profile blob.