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I have found an example for clearing all symbol definition by:

ClearAll["Global`*"]

But what does the symbol ` mean? It isn't the apostrophe ', yet it is not documented in Mathematica help.

Jim

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    $\begingroup$ It's a backtick. See this. $\endgroup$ – J. M. will be back soon Jun 10 '13 at 17:27
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    $\begingroup$ It's related to the concept of Context in Mathematica, see this. $\endgroup$ – mmjang Jun 10 '13 at 17:28
  • $\begingroup$ @0x4A4D you are so fast! $\endgroup$ – mmjang Jun 10 '13 at 17:30
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    $\begingroup$ You can learn a bit about the symbol ` in a different context than Context, see this: Meaning of backtick in floating-point literal $\endgroup$ – Artes Jun 10 '13 at 17:36
  • $\begingroup$ Thanks, this is solved. How can I mark one of the comments as an answer? $\endgroup$ – JimmyLin Jun 10 '13 at 18:54
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In Mathematica, the back-tick or grave accent ( ` ) is used for two purposes:

  1. As a context mark to delimit contexts (name spaces) in the full name of a variable.

  2. As a number mark to mark the end of an approximate number, and separate the number from its precision value.

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  • $\begingroup$ and what does that * symbol mean? I see in the documentation that it is used just in the Generalization & Extensions part. But I couldn't find the documentation about it? $\endgroup$ – Sepideh Abadpour Sep 20 '15 at 21:10
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    $\begingroup$ I'm guessing your are asking about the * in ClearAll["Global`*"]. That * means zero-or-more-characters. It is documented here under Abbreviated String Patterns. BTW, posting your question as a comment to my answer is most inappropriate. It has nothing to do with my answer and nothing to do with the original question. In the future, please keep your posts on-topic. $\endgroup$ – m_goldberg Sep 21 '15 at 4:15
  • $\begingroup$ ok, I thought it will be a duplicate if I post a new one! $\endgroup$ – Sepideh Abadpour Sep 21 '15 at 4:41
  • $\begingroup$ @m_goldberg though to be fair, the question was about what ` means in the command ClearAll["Global`*"], and your answer mentioned the meanings of ` in general but did not discuss its use in this context. $\endgroup$ – WillG Nov 14 at 18:56

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