A bit (b) is the simplest unit of storage and can store only 2 things (1 or 0).
Since a single bit is of limited utility, we group them together into bytes.
A byte (B) is made up of 8 bits and is THE basic unit of storage in a computer. We can store 256 things in a single byte (2^8) with values from 0 - 255. As you might guess, the more bytes that we have, the more information we can store.
In the old days, a kilobyte was considered to be a lot, but today, we speak in megabytes and gigabytes and terabytes.
[note that it takes larger addresses to be able to address all of these bytes. [see powers of 2]
The chart below shows the different prefixes used to denote larger and larger collections of bytes.
A kilobyte or "K" is about a thousand; "M" a million; "G" a billion; ...
A flopppy holds 1.44 Megabyes, a Zip disk holds about 100 Megabytes, a CD holds about 650 Megabyes, a typical thumbdrive holds 4+ Gig and a typical DVD holds 4.7 Gigabytes (9.4 double sided). It would take 213 regular DVDs to make a Terabyte and over 21,000 DVDs to make a Petabyte!!
So a Yottabyte, or a "Y", is huge, almost beyond comprehension. A "Y" is 1 septillion, 208 sextillion, 925 quintillion, 819 quadrillion, 614 trillion, 629 billion, 174 million, 706 thousand, one hundred and seventy-six.
So remember: if you got a "Yott", you got a LOT...