Q: What's all this about kilobytes, megabytes, gigabytes and what have you?

A: First, a bit is a single binary digit in memory (a zero or a one):

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A byte is a contigous block of 8 bits in memory:

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A word is a contiguous block of bytes, typically 4 of them:

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A kilobyte (abbreviated KB) is contiguous block of 210 bytes, which is 1,024 bytes, which is approximately 1,000 bytes:

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Whew!

A megabyte (abbreviated MB) is 220 bytes, which is 1,048,576 bytes, which is approximately 1,000,000 (a million) bytes.

A gigabyte (abbreviated GB) is 230 bytes, which is 1,073,741,824 bytes, which is approximately 1,000,000,000 (a billion) bytes.

A terabyte (abbreviated TB) is 240 bytes, which is 1,099,511,627,776 bytes, which is approximately 1,000,000,000,000 (a trillion) bytes.

A petabyte (abbreviated PB) is 250 bytes, which is 1,125,899,906,842,624 bytes, which is approximately 1,000,000,000,000,000 (a quadrillion) bytes.