inside single quotes ' nothing will be parsed, so $var won't be
replaced with its content. This one is good for echo'ing larger
html tags, but you need to close and re-open the strings when
using a var
$var = 'hello, ' . $name . ' !';
$var = 'hello, $name !'; //output: hello, $name !
double quotes:
$name = 'max';
$var = "hello, $name !"; // output: hello, max !