What are KB, MB, TB & PB?
KB, MB, TB and PB are units of measurement for computer storage and memory.
A bit is a binary digit, the smallest increment of data on a computer. A bit can hold only one of two values: 0 or 1, corresponding to the electrical values of off or on, respectively. Because bits are so small, you rarely work with information one bit at a time. Bits are usually assembled into a group of eight to form a byte.
A byte contains enough information to store a single ASCII character, like "h".
A kilobyte (KB) is 1,024 bytes, not one thousand bytes as might be expected, because computers use binary (base two) math, instead of a decimal (base ten) system.
Computer storage and memory is often measured in megabytes (MB) and gigabytes (GB). A medium-sized novel contains about 1MB of information. 1MB is 1,024 kilobytes, or 1,048,576 (1024x1024) bytes. Similarly, one 1GB is 1,024MB, or 1,073,741,824 (1024x1024x1024) bytes.
A terabyte (TB) is 1,024GB; 1TB is about the same amount of information as all of the books in a large library, or roughly 1,610 CDs worth of data.
A petabyte (PB) is 1,024TB (terabytes).
An exabyte (EB) is 1,024PB.
A zettabyte (ZB) is 1,024EB.
Finally, a yottabyte (YB) is 1,024ZB
