Nicholas on Nostr: what is pubkey?

{ "id": "e470dfae0dc3fd1303d541c4ee778ee6f5ff84c2f35b1dc30b45e89cb10e04f3", "pubkey": "316dd1215bcf94d93ab32cd5fbe541b46680e4a59f824173cc265c65d2dce984", "created_at": 1707584747, "kind": 1, "tags": [ [ "e", "4a8719c7f290b5682f49a095e07843f9dec4cbe92a69208bb22fbaa99cca82d2", "", "reply" ], [ "p", "ee6ea13ab9fe5c4a68eaf9b1a34fe014a66b40117c50ee2a614f4cda959b6e74" ] ], "content": "what is pubkey?", "sig": "6e5caa015cecfaed6849dcf59d3dd7155e240c94075c28b49b1c4b065d00cb942209a206e48d9232d692df676e43506534d43072f30dce2d1789daeeb9b16cad" }