This follows the news of the last IPv4 blocks being issued by the Internet Assigned Numbers Authority (IANA) to Regional Internet Registrys in February last year. Asia-Pacific Network Information Centre (APNIC) ran out of addresses to allocate for the Asia-Pacific region 2 months later.
IPv4 uses 32 bits for addresses, giving a maximum possible 4.3bn addresses to allocate for devices to connect to the internet. IPv6 is a replacement for IPv4, with support for 128 bit addresses (3.4 × 10^38 addresses). As of June this year, IPv6 only has 0.2% of internet traffic, with sales of unused IPv4 addresses gaining steam.