The IPv4 protocol enabled the allocation of more than four billion IP addresses, which seemed to be more than enough at the moment it occurred.
ICANN has informed the public that approximately 10 percent of IP (about 400 million) addresses are still available, meaning they are still not allocated. These addresses are expected to be allocated in the following two years. Since all allocated addresses are still not used, the actual lack of IPv4 addresses will not be noticed in the near future. Because there are not many IPV4 addresses left, it is clear that the migration to the IPv6 addressing system needs to be planned. This system will enable the registration of 340282366920938463463374607431768211456 addresses compared to 4294967296 addresses within the IPv4 protocol.
Additional information on the IPv6 protocol is available here.