Does anyone know, what is the actual reason behind "dollar variable notation" in some of the scripting languages, i.e. PHP or Perl? Python creators did not find $variable useful, neither do I. Why does PHP and Perl force me to press shift-4 so often?

(OK, in Perl you can somehow explain it with distinguishing $scalar, @array and %hash but still it could be successfully avoided there, type does not need to be explicit)

I don't know if this is the main reason, but if PHP did not have variables with an identifying marker, the following would not be possible.

echo "Welcome back $name, we last saw you on $date";

Update:

It also creates something called a variable variable possible. The usefulness of a variable variable is debatable though, and I wouldn't recommend anyone making regular use of them.