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Kibibit (Kib, Kibit) - 1024 bits (= 128 bytes).
The SI (International System of Units) defines the prefix "kilo-" to be exactly 1 000. In computer usage this is usually approximated with 1 024 (2^10).
All goes well, until storage gets into Gigabyte magnitudes. You see, 2^30 is 1 073 741 824, which is 7% more than 1 billion. So someone came up with the idea to make a new set of prefixes for powers of two.
But not everyone is adopting these prefixes. When you see GB on a hard drive, it's 1 000 000 000 bytes (a billion bytes), but when you see it on your computer it's usually 1 073 741 824 bytes. Except GNOME, which uses Gibibytes.
Also the nickname of a chatter of #twokinds.

Bit Short for "binary digit", is the lowest unit of data in current electronic computers. Takyoji is wrong here. Abbreviated sometimes b.
>Okay, I didn't see the post time, I usually don't look at them... but still... it's been like that for 3 years?
Nibble - Half a byte (4 bits), not 1/5 - 1/8 bytes.
Byte - also called an octet, this is 8 bits, save for some old IBM mainframes that have 9-bit bytes. Abbreviates sometimes B, which also means Bel, but Bel is mostly used in decibel (dB) so....

Kilobit - 1000 bits. Abbreviated kb.
Kibibit - see above.
Kilobyte - Exactly 1 000 bytes, or equal to 1 Kibibyte. Abbreviated kB. Notice the capitalization.
Kibibyte (Kib, Kibit) - 1,024 bytes.

Megabit (Mb) - 1 000 000 bits.
Mebibit (Mib, Mibit) - 1 048 576 bits, or 131 072 bytes.
Megabyte (MB) - 1 000 000 bytes, or equal to 1 Mebibyte.
Mebibyte (MiB) - 1 048 576 bytes. 1024 times larger than a Kibibyte.


Gigabit (Gb) - 1 000 000 000 bits.
Gibibit (Gib, Gibit) - 1 073 741 824 bits, or 134 217 728 bytes.
Gigabyte (GB) - 1 000 000 000 bytes, or equal to 1 Gibibyte.
Gibibyte (GiB) - 1 073 741 824 bytes. 1024 times larger than a Mebibyte.

And so we have a slew of units, each 1000 or 1024 times larger than the one before, Terabyte/Tebibyte, Petabyte/Pebibyte, Exabyte/Exbibyte, Zettabyte/Zebibyte and...

Yes, there still are units larger than Zebibyte!
Yottabit (Yb) - 1 000 000 000 000 000 000 000 000 bits.
Yobibit (Yib, Yibit) - 1 208 925 819 614 629 174 706 176 bits, or 151 115 727 451 828 646 838 272 bytes.
Yottabyte (YB) - 1 000 000 000 000 000 000 000 000 bytes, or equal to 1 Yobibyte.
Yobibyte (YiB) - 1 208 925 819 614 629 174 706 176 bytes. 1024 times larger than a Zebibyte. As you can see, it's 20% larger than a Yottabyte...

digitalizer - Another name for graphics tablet, as it takes real-world positions and turns them into digits.
dB (Decibel) - A unit for ratio between two values in logarithmic, commonly used in electrical engineering, to describe sound volume and pressure... Umm, can I point to Wikipedia for this?

I prefer to consider the difference that hard drive manufacturers lie to you and sane people believe in the holy powers of two, Kakurady. ;) Trying to introduce new units to sync with the metric system is simply going to confuse people. And considering I have two degrees and a membership in the IEEE, and your post is the first I've ever heard of those units of measure, my suspicion is that the rest of the computer world rather agrees with me. I could be wrong, but that's my suspicion. Can you source me that one please?

You're right, a decibel is a unit for ratio between two values, generally as measured on a logarithmic scale because decibels fit nicely on a logarithmic scale. It's used to measure energy, thus its use in frequency analysis. The confusing thing about decibels is that, as a unit of ratio, they are effectively unitless themselves.

-- Intriguing --
This is a rather fascinating discussion. I don't have access to the authoritative dictionary, but the Standards Activities Board voted to accept without enforcing the new terms in 2002. In other words, while the new terms are acceptable, so are the old ones as powers of two, and it's generally recommended that anyone using kB as SI-adapted make sure to note the ambiguity. Considering the lack of their use in education, I doubt we'll see any sort of full adoption of them any time soon. Now, I don't know what the official Standards Board decided, however, I only found some SAB minutes I could get access to.

Maybe I should email some of my old professors. I don't think my student id will get me into the library anymore to check the IEEE 100 with their references, and I'm kind of poor to buy subscription to the digital library just for this...

Wikipedia (Template:Quantities of bits and Kibibyte - also check out citation #1 - http://www.iec.ch/zone/si/si_bytes.htm ), GNOME System Monitor, or just join #twokinds and ask Kibi. (Note: I'm not Kibi.)

I'll probably continue to say Megabyte over Mebibyte however.