How does IPv6 addressing differ from IPv4?

IPv6 is 128 bits (vs IPv4's 32), written as 32 hexadecimal digits in colon-separated groups of four, and is not case-sensitive.

IPv6 (Internet Protocol version 6) exists because the 32-bit IPv4 space — about 4 billion addresses — ran out as the internet grew. By going to 128 bits it provides an effectively unlimited supply of addresses. The trade-off is that 128 bits would be unreadable in decimal, so IPv6 is written in hexadecimal instead, which is far more compact.

How the notation works:

• Every 4 bits map to 1 hex digit, so 128 bits = 32 hex digits total
• Those 32 digits are grouped into eight blocks of four, separated by colons (:) instead of IPv4's periods
• It is not case-sensitive — ACAD and acad mean the same thing, so you can type lowercase for convenience

Example: 2001:0db8:acad:0001:0000:0000:0000:0001

Go deeper:

• IPv6 (Wikipedia) — the 128-bit address, hexadecimal notation and why IPv4 exhaustion drove its adoption.
• IPv4 (Wikipedia) — the 32-bit predecessor IPv6 is compared against.