Erreur Node JS Package Nodemon

nodemon : The term 'nodemon' is not recognized as the name of a cmdlet, function, script 
file, or operable program. Check the spelling of the name, or if a path was included, 
verify that the path is correct and try again.
At line:1 char:1
+ nodemon mod.js
+ ~~~~~~~
    + CategoryInfo          : ObjectNotFound: (nodemon:String) [], CommandNotFoundExcepti 
   on
    + FullyQualifiedErrorId : CommandNotFoundException
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