syntax - What does ":" mean in PHP?

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What is “:” in PHP?

What does the : mean in the following PHP code?

    while (have_posts()) : the_post();
?>

Answer

It's called an Alternative Syntax For Control Structures. You should have an endwhile; somewhere after that. Basically, it allows you to omit braces {} from a while to make it look "prettier"...

As far as your edit, it's called the Ternary Operator (it's the third section). Basically it's an assignment shorthand.

$foo = $first ? $second : $third;

is the same as saying (Just shorter):

if ($first) {
    $foo = $second;
} else {
    $foo = $third;
}