A header is technical information embedded within an image file that provides important data about the file. This may include details such as image dimensions (width and height in pixels), file format, resolution, and other attributes used for displaying the image correctly.
Headers can also contain identifying information, such as the file name, source, or ownership metadata. Understanding headers is important for photographers and digital editors, as they help manage, organise, and ensure proper handling of image files across different software and platforms.