The Internet Is Full

In April, ARIN, the American Registry for Internet Numbers, announced that it had reached 'phase 4' of its IPv4 countdown plan, with fewer than 17 million IPv4 addresses remaining. There is no phase 5.
Unlike most of the other protocols, which were never intended to underpin global networks, IP is the Internet Protocol, designed to interconnect all kinds of smaller networks into a unified, global one. As such, making the addresses a meager 32 bits was a big failure of imagination. That's only ten digits when written down as a regular decimal number.