What is the type of return value of PHP's microtime()?
    $start = microtime();
    // ...
    $end = microtime();
    echo $end - $start;

When we make this code running, say that the output is 0.406643. Does this mean the code piece ran over 0.4 seconds or 0.4 microseconds?
What is the type of return value of PHP's microtime()?
===

    $start = microtime();
    // ...
    $end = microtime();
    echo $end - $start;

When we make this code running, say that the output is 0.406643. Does this mean the code piece ran over 0.4 seconds or 0.4 microseconds?