What is an IPv6 Address ?

An IPv6 address is a 128-bit numerical label assigned to each device connected to a computer network that uses the Internet Protocol version 6 (IPv6) for communication. It serves the same functions as an IPv4 address: identifying the host or network interface, and providing the location of the host in the network.

An IPv6 address is typically represented in the form of eight groups of four hexadecimal digits separated by colons, also known as "colon-hexadecimal" notation. Each group of four hexadecimal digits represents 16 bits, referred to as a hextet. For example, the IP address "2001:0db8:85a3:0000:0000:8a2e:0370:7334" is made up of eight hextets: 2001, 0db8, 85a3, 0000, 0000, 8a2e, 0370, and 7334.

Each IP address can be divided into two parts: the network prefix and the interface identifier. The network prefix identifies the network that the host is connected to, while the interface identifier identifies the specific host within that network.

IPv6 addresses have a larger address space than IPv4 addresses, which allows for more efficient use of IP address space. IPv6 addresses are globally unique and are used to identify devices on the internet.

IPv6 also includes new features such as support for autoconfiguration, which allows devices to automatically configure their IP addresses without the need for DHCP, and improved security through the use of IPsec.

It's important to mention that IPv6 addresses can be grouped in a CIDR block and CIDR blocks can be used to create a VLSM(Variable Length Subnet Mask) which allows a network administrator to divide an IP address space into subnets of different sizes, depending on the needs of the network. This is more efficient than using a fixed subnet mask because it allows the administrator to use the available IP address space more effectively.