Don't try and learn IPv6 from this guy

Quoting:32-bit (4-byte) addresses, which limits the address space to 4,294,967,296 (2 to the 32nd power) possible unique addresses.

Quoting:...(about 3.4 × 10 to the 38th power) addresses, or approximately 5 × 10 to the 28th power addresses for each of the roughly 6.5 billion people alive today. In a different perspective, this is 2 to the 52nd power addresses for every star in the known universe – a million times as many addresses per star than IPv4 supported for our single planet.

Quoting:Using auto-configure mode the last 48 bits is the MAC address. The first 48 bits is the network address. The remaining bits identify type of traffic and priorities, allowing easier firewalls and routing.

Quoting:8.3. The size of IPv6's address space

Compared to IPv4, IPv6 has a seemingly endless amount of address space. While superficially true, short-sighted and wasteful allocation policies could also result in the adoption of practices that lead to premature exhaustion of the address space.

It should be noted that the 128-bit address space is divided into three logical parts, with the usage of each component managed differently. The rightmost 64 bits, the Interface Identifier [RFC2373], will often be a globally-unique IEEE identifier (e.g., mac address). Although an "inefficient" way to use the Interface Identifier field from the perspective of maximizing the number of addressable nodes, the numbering scheme was explicitly chosen to simplify Stateless Address Autoconfiguration [RFC2462].

The middle 16 bits of an address indicate the subnet ID. Per [RFC 3177, RIRs-on-48s], this field will often be inefficiently utilized, but the operational benefits of a consistent width subnet field were deemed to be outweigh the drawbacks.

The decisions to inefficiently utilize the bits to the right of /48 were made under the knowledge and assumption that the bits to the left of /48 would be managed prudently and that if done so, will be adequate for the expected lifetime of IPv6 [RFC3177].