We never can be sure of anything 100%. But we can reach good enough confidence.
The Proof union uses objective data to create a way to provide a confidential level about declared information.
High-level confidence proof examples
Emails and phones - use confirmation codes
Public keys - create a signature with a private key
DNS name - create TXT record with check information
2FA auth application - enter the code
Swarm intelligence proof
For some cases, we use a group of people who can validate some information.
As an example, decentralized processes, like "KYC".