What happens when there are two same IP addresses? IPv4 addresses run out few years ago. But everywhere I can see mine or someone elses IP address it's in IPv4, not IPv6. I understand that world switched to IPv6? So why we can see address in older format? Does that mean somewhere someone can have same address as I? How can that work?
ISPs asign one IPv4 address to a customer, and your "WiFi box" acts as a router/NAT box/ DHCP server doling out addresses from a private range internally. It is possible that the "outside" IPv4 address is itself in a private range, leaving your ISP through a mere handful  of IPv4 addresses via NAT (real one, your box really does PAT, port forwarding through one IPv4 address).