• May be declared in a local scope with a my qualifier
• Required under use strict
• Helps avoid common mistakes
• Limits the variable to its enclosing block
• Declaring a variable without assigning a value leaves its value undefined
• May declare a variable and assign a value in the same statement

        use strict;

        my $apple_variety;                # Value undefined
        $apple_variety = "Red Delicious"; # Defined
        $apple_vareity = "Granny Smith";  # Error

        my $apple_color = "red";          # Declare and define