# What does the "$" symbol mean in Mathematica programming? [duplicate] I cannot find any reference to the$ in the Mathematica documentation, yet I frequently see it used, especially on StackExchange.

In[23]:= $= 3 Out[23]= 3  It is common to name package constants with a symbol starting with $, but this is just a convention.
• I think "constant" is not quite the best word for it. I'd rather say "global variables that are not supposed to be messed with by the user". E.g., $ContextPath is meant to be change frequently -- alas only by the system, not by the user. Nov 9, 2022 at 10:47 It has no inherent meaning, but it is used by convention as a prefix for many system parameters and special-purpose symbols. Look at Names["System$*"]

Module[{x}, x]
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