In PHP, what are some common pitfalls to avoid when manipulating timestamp values, such as division by 1000 for milliseconds to seconds conversion?

When manipulating timestamp values in PHP, a common pitfall to avoid is mistakenly dividing by 1000 to convert milliseconds to seconds. This error occurs because PHP's `time()` function returns the current Unix timestamp in seconds, not milliseconds. To correctly convert milliseconds to seconds, you should divide by 1000 only if the timestamp is in milliseconds.

// Incorrect way of converting milliseconds to seconds
$milliseconds = 1629261378000;
$seconds = $milliseconds / 1000; // Incorrect conversion

// Correct way of converting milliseconds to seconds
$milliseconds = 1629261378000;
$seconds = $milliseconds / 1000; // Correct conversion