What is the difference between :: and ::1?
Answer
::/128 is the unspecified address, used as a source before a host has one; ::1/128 is loopback
One character apart and entirely different jobs. The unspecified address appears as a source when a host has not yet committed to an address — duplicate address detection is the standard case. Loopback is ::1, the IPv6 equivalent of 127.0.0.1. Swapping them is a common note-taking error. They are not the same address: :: is 128 zero bits and ::1 has the last bit set, and zero compression does not erase a significant 1. The wildcard reading comes from firewall syntax, where ::/0 rather than ::/128 is the match-anything prefix.