What is the correct way to define a backslash (\) in a PHP variable?

When defining a backslash (\) in a PHP variable, you need to escape it using another backslash. This is because the backslash is a special character in PHP and is used for escaping characters. So if you want to include a backslash in a PHP variable, you need to use two backslashes to represent a single backslash.

// Define a variable with a backslash
$backslash = "\\";

// Output the variable
echo $backslash;