What are the differences between using a period, comma, or plus sign in concatenating strings in PHP, and how does it impact the outcome of the code?

When concatenating strings in PHP, the period (.) operator is used to combine two strings together. The comma (,) is used to separate arguments in functions or echo statements, but it does not concatenate strings. The plus sign (+) is used for arithmetic operations and cannot be used for string concatenation. Using the correct operator is crucial to ensure the desired outcome of the code.

// Using the period operator for string concatenation
$string1 = "Hello";
$string2 = "World";
$concatenatedString = $string1 . " " . $string2;
echo $concatenatedString;