Let's say you have a variable that contains fruit.
$fruit = "banana apple orange grape";
The .= operator can be used to append values to the end of the variable. In this example, pineapple will be appended to the $fruit variable.
$fruit .= "pineapple";
The variable can be printed.
The original values in the variable plus pineapple will be printed.
banana apple orange grape pineapple