The Internet Protocol version 4 (IPv4) was created in the 1980s. At the time, nobody imagined we would have billions of people, smartphones, and smart toasters all needing their own connection. IPv6 is the modern solution to that growth.
Uses 32-bit addresses written in decimal. The "address exhaustion" issue means we can't easily add new devices to the open web anymore.
Uses 128-bit addresses written in hexadecimal. It has enough space to give every grain of sand on earth its own unique phone number.
IPv6 headers were redesigned to be much smaller and simpler, which means routers can process packets faster.
Because every device can have its own public IP, you no longer need complex "NAT traversal" tricks for gaming or VoIP.
IPv6 was also designed with security in mind from the start, supporting IPSec (encryption and authentication) natively, and features Auto-Configuration (SLAAC) so devices can set themselves up instantly.