IP addresses let machines communicate across a network. DigitalOcean Droplets are assigned IPv4 addresses by default. Enabling IPv6 on a Droplet gives you access to its 16 additional IPv6 addresses.
IPv6 is the most recent version of the IP protocol. In addition to improvements on the protocol itself, IPv6’s massive increase in available address space makes it less vulnerable to brute force–style security exploits, like ones which scan an entire address space searching for vulnerabilities.
By default, each Droplet with IPv6 enabled is allotted a /124 subnet, which contains 16 configurable IPv6 addresses. One IPv6 address in this range is configured for the Droplet by default, and you can configure additional IPv6 addresses at any time.