What does the "$" character mean in Ruby?

$ identifies a global variable, as opposed to a local variable, @instance variable, or @@class variable.

Among the language-supplied global variables are $:, which is also identified by $LOAD_PATH

$: is the global variable used for looking up external files.

From http://www.zenspider.com/Languages/Ruby/QuickRef.html#18

$: Load path for scripts and binary modules by load or require.

I wanna note something weird about Ruby!

$ does indeed mean load path. And ; means "end line". But!

$; means field separator. Try running $;.to_s in your REPL and you'll see it return ",". That's not all! $ with other suffixes can mean many other things.

Why? Well, Perl of course!