Concatenation

Concatenation is the PHP feature that appends two strings together, to make a third, longer one.

Concatenation is also achieved with interpolation, inside a string; by calling echo, multiple times or with multiple arguments; by using the join() function.

Concatenation is done with the dot operator ..

<?php

    $a = "world";
    $b = "Hello ";
    echo $b . $a;
    // displays Hello world

?>

Documentation

See also All String Concatenations in PHP.

Related : String, Interpolation, Heredocs, __toString() Method, implode()