IPv6

128-bit long address.

FFFF:0000:0000:0000:0000:0000:0000:FFFF  - my observation: each letter in an address is /4 for prefix length. Like(network part in bold):

• F000::1/4
• FF00::1/8, etc.
  

2000::/3 - stands for global unicast address prefix.
FD00::/8 - unique local unicast address prefix.

FE80::/10 - link local unicast address prefix. Using for functions, which don't need to leave the subnet. No specific configuration is required, because a host forms these addresses by using the first 10 bits of hex FE80 (binary 1111111010), 54 more binary 0s, and the last 64 bits being the host’s EUI-64 format interface ID. For example, hosts use this address for NDP RS messages.

FF00::/8 - stands for multicast address prefix.
FF02::/16 - multicast that stay on the local link.
::1 - represents loopback address.
:: - reserver address which can be used when host doesn't know his IPv6 address and is trying to discover it.
FF02::1:2 - reserved for hosts to be used when searching for unknown DHCP server.

Interface ID and EUI-64 Format

MAC addresses are 6 bytes (48 bits) in length, so for a host to automatically decide on a value to use in the 8-byte (64-bit) interface ID field, IPv6 cannot simply copy just the MAC address. To complete the 64-bit interface ID, IPv6 fills in 2 more bytes. Interestingly, to do so, IPv6 separates the MAC address into two 3-byte halves, and inserts hex FFFE in between the halves, to form the interface ID field, as well as setting 1 special bit to binary 1. EUI-64 format requires setting the seventh bit in the first byte of MAC-address to binary 1. The underlying reason is that Ethernet MAC addresses are listed with the low-order bits of each byte on the left, and the high-order bits on the right.

Dynamic IPv6 address autoconfiguration.

IPv6 supports two methods of dynamic configuration of IPv6 addresses. One uses a stateful DHCPv6 server and another uses stateless autoconfiguration.

Stateless autoconfiguration uses two NDP messages, namely router solicitation (RS) and router advertisement (RA) messages, to discover the IPv6 prefix used on a LAN.
The host sends the RS message as an IPv6 multicast message, asking all routers to respond to the questions “What IPv6 prefix(s) is used on this subnet?” and “What is the IPv6 address(s) of any default routers on this subnet?” IPv6 does not use broadcasts.

IPv6 Transition Options