What is the difference between these in php

Question

One has dot and the other doesn't. I have seen this several times but i have not been able to figure out the role of the dot(.) Before the equal sign

Answer 1

It's a concatenation assignment operator for strings.

$txt1 = "Hello, "
$txt2 = "World!"
$txt1 .= $txt2
echo $txt1 // "Hello, World!"

https://www.w3schools.com/php/php_operators.asp

Answer 2

Thanks bro