Self Sovereign Identity (SSI) is an umbrella term well-detailed by Christopher Allen, and inspired by many in the Identity community before him, in his 2016 blog post: The Path to Self-Sovereign Identity, which identifies Ten Principles of Self-Sovereign Identity:
We’re committed to an open software delivery model and therefore want to share our roadmap to Web 5.
Web 5 is a decentralized platform that provides a new identity layer for the web to enable decentralized apps and protocols.
In the current web model, users do not own their data or identity. They are given accounts by companies and their data is held captive in app silos. To create a new class of decentralized apps and protocols that put individuals at the center, we must empower them with self-owned identity and restore control over their data.