Question

if(true):
    echo 'good';
endif;

I’ve only see it in PHP today!

I’ve always been using:

if(true)
{
   echo 'good';
}

Answer 1

It is the Alternative syntax for control structures.

Quoting that page of the manual :

PHP offers an alternative syntax for
some of its control structures;
namely, if, while, for,
foreach, and switch. In each case,
the basic form of the alternate syntax
is to change the opening brace to a
colon (:) and the closing brace to
endif;, endwhile;, endfor;,
endforeach;, or endswitch;,
respectively.

I don’t often see it used in “pure PHP” files, but it’s quite often used when PHP is mixed with HTML in the same file — i.e. when used as a templating language.