(1) Web of Trust is another old concept, 1992 I believe, that has gotten a new life. It says, that over time you will accumulate a whole bunch of interconnected trust anchors – basically endorsements – from trusted parties.
Some of them will be formal, like from governments, official agencies or large enterprises like banks or tech companies, while others might be quite informal, like your brother or sister, your teacher or coach. But together they’ll form a strong web of trusted parties that add validity to your digital identity, decentralized, without the need for a central authority, without a central point of control. Or failure.