What PHP functions can be used to format numbers with commas for display purposes?

When displaying large numbers in PHP, it is often helpful to format them with commas for better readability. This can be achieved using the number_format() function in PHP. This function takes a number as input and returns a formatted version with commas separating the thousands.

$number = 1000000;
$formatted_number = number_format($number);
echo $formatted_number; // Output: 1,000,000