Self-sovereign identity—commonly abbreviated SSI—is a new model for digital
identity on the internet: i.e., how we prove who we are to the websites, services, and
apps with which we need to establish trusted relationships to access or protect private information.
Driven by new technologies and standards in cryptography, distributed networks, cloud computing, and
smartphones, SSI is a paradigm shift for
digital identity similar to other technology paradigm shifts: for example, the shift
from keyboard-driven user interfaces (e.g., MS-DOS) to graphical user interfaces
(e.g., Windows, Mac, iOS), or the shift from dumb phones to smartphones.
SSI is an evolution of the identity layer of the internet, it will enable a more secure, private,
and trustful internet.
It is based on
Public-Key Cryptography,
you and only you control and own your private key.
The world will know you by your public key, and only you can prove ownership of the private key.
This makes it so that your identity is not tied to a centralized authority (single point of
failure).
In other words (also from Chapter 1):
A person's identity that is neither dependent on nor subjected to any other power or state