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A petabyte is a huge amount of space on a computer — for files, photos, films, or science data. In the official counting system it is 1,000 trillion : a 1 with 15 zeros after it. A is a tiny piece of computer memory; a petabyte is that tiny piece multiplied until the number stops feeling real. People write it PB. You will not meet a petabyte on a school laptop. The word belongs to data centres, big labs, and news about how much of the internet someone is storing. Though actually, computer people also have a unit called a pebibyte, which counts by twos rather than by thousands. When a hard-disk box says petabyte, it almost always means the thousand-trillion counting — and that number is the smaller of the two, so the drive sounds bigger. The piece peta- is the same peta- as in : it always marks that huge “thousand trillion” step.
拍位元組（PB）。台灣說「位元組」，大陸說「字节」。
組成peta- (the SI prefix for a thousand trillion, 10^15; named from Greek penta, “five”, because it is the fifth of those 1,000-times-bigger steps) + byte (the basic unit of computer memory). Byte itself was coined from bite.
原始詞典資料2 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
petabytenoun/ˈpɛtəbaɪt/
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One quadrillion (10¹⁵, or 1,000,000,000,000,000) bytes or 1,000 terabytes.
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informalcomputingengineeringmathematicsA pebibyte.
- As we moved along that progression, we went from the folder analogy to the file cabinet analogy to the library analogy to — well, at petabytes we ran out of organizational analogies. At the petabyte scale, information is not a matter of simple three- and four-dimensional taxonomy and order but of dimensionally agnostic statistics.
- The Hadron Collider has gone from producing 320 terabytes of data a week to a petabyte a second. In short, it has been said that the total amount of data created worldwide in 2011 was about one zetabyte^([sic]) (or 1,000,000 petabytes) and that this figure will increase by 50%–60% in each subsequent year.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。