What are the backticks `` called?

Question

What are the backtick operators (``) called in the context of evaluating their content?

Answer 1

Backticks (``) is an Execution Operator. PHP will attempt to execute the contents of the backticks as a shell command; the output will be returned (i.e., it won't simply be dumped to output; it can be assigned to a variable). Use of the backtick operator is identical to shell_exec().

Eg.

$output

"; ?>

For more info refer: http://php.net/manual/en/language.operators.execution.php