How can headers be manipulated to store and retrieve information in JPEG files using PHP?

Headers in JPEG files can be manipulated using PHP by using the `getimagesize()` function to retrieve information about the image file, including its headers. To store information in the headers of a JPEG file, you can use the `exif_read_data()` function to read the existing headers, modify them as needed, and then write them back to the file using the `exif_write_data()` function.

// Get image file headers
$image_info = getimagesize('image.jpg');

// Read existing headers
$exif_data = exif_read_data('image.jpg');

// Modify headers as needed
$exif_data['UserComment'] = 'This is a custom comment';

// Write modified headers back to the file
exif_write_data($exif_data, 'image.jpg');