if you are echoing php directly into html i like to do this
=$variable?>
much shorter than writing the whole thing out (php echo blah blah)
if you are writing html in php directly then there several options
$var = ''.$variable.''; // concatenate the string
$var = "$variable"; // let php parse it for you. requires double quotes
$var = "{$variable}"; // separate variable with curly braces, also requires double quotes