What is $Resource global value provider in Salesforce?

The $Label global value provider enables you to access labels stored outside your code. The $Locale global value provider returns information about the current user's preferred locale. The $Resource global value provider lets you reference images, style sheets, and JavaScript code you've uploaded in static resources.

list of Global value providers in Salesforce:

$globalID
$Browser
$Label
$Locale
$Resource

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