PHP echo is a language construct, not a function. Therefore, you don't need to use parenthesis with it. But if you want to use more than one parameter, it is required to use parenthesis.
The syntax of PHP echo is given below:
void echo ( string $arg1 [, string $... ] )
PHP echo statement can be used to print the string, multi-line strings, escaping characters, variable, array, etc. Some important points that you must know about the echo statement are:
<?php echo "Hello by PHP echo"; ?>
<?php echo "Hello by PHP echo this is multi line text printed by PHP echo statement "; ?>
<?php echo "Hello escape \"sequence\" characters"; ?>
<?php $msg="Hello rookienerd PHP"; echo "Message is: $msg"; ?>