What is actually inside an image file
A photo isn’t just pixels. It carries the camera, the settings, the time, often the exact location and sometimes a serial number.
Open a photo in a text editor and most of it is unreadable compression data. Scattered through the first few kilobytes, though, is a surprising amount of plain text.
The layers
Every image format is a container and the picture is only one of the things in it.
The image data is the bulk: the compressed pixels, in whatever scheme the format uses.
EXIF is what the camera wrote. Make, model, lens, shutter speed, aperture, ISO, focal length, whether the flash fired, the orientation the camera was held at, the date and time and on a phone, almost always, the coordinates. Many cameras also write the body serial number.
The colour profile describes how the numbers in the file map to real colours. It is technical rather than personal and removing it can visibly shift the colours on a wide-gamut screen.
XMP is Adobe’s metadata format, which editors use for ratings, keywords, copyright and edit history. It sits alongside EXIF rather than replacing it.
Thumbnails. Many cameras embed a small preview so devices can show it instantly. There is a well-known failure mode where a photo is cropped or edited but the embedded thumbnail still shows the original, which has exposed things people intended to remove.
Orientation, the field you have already noticed
EXIF orientation is why photos sometimes appear sideways. The sensor captured a landscape image and wrote a tag saying “rotate this 90 degrees when displaying”. Software that honours the tag shows it upright; software that ignores it shows it on its side. The pixels are identical in both cases.
This is also why a photo can look correct in one app and wrong in another and why stripping metadata occasionally rotates an image unexpectedly. A tool that removes the orientation tag without rotating the pixels has changed how the photo displays.
Which fields are worth caring about
For most people, three.
Location, because it is precise and invisible. A photo of a living room posted to a forum has told everyone reading where that living room is.
Serial numbers, because they link otherwise anonymous photos to each other and eventually to a purchase record.
Timestamps, because the gap between when a photo was taken and when it was last modified is often more informative than either date alone.
Seeing it for yourself
The quickest way to understand how much is in there is to look at one of your own photos, ideally one straight off a phone rather than one that has been through a messaging app. The EXIF viewer shows everything it finds, with the coordinates first if they’re present.
Common questions
Does every image have metadata?
No. Cameras and phones write a lot of it, editors write some and screenshots often have almost none. Images that have been through a social platform usually arrive stripped, because most platforms remove metadata on upload, though you can’t count on any particular one doing so.
Can metadata prove a photo is real?
No. Every field is plain text that any tool can write, so metadata can be edited or fabricated as easily as it can be removed. It is a useful hint on an unremarkable file and no evidence at all on one that someone had a reason to alter.
Is GPS data really in my photos?
If location services were enabled for the camera, yes, usually to within a few metres. It is the field with the most real-world consequence, which is why it is worth checking before posting a photo taken at home.
Does metadata make my files bigger?
Only slightly. A typical EXIF block is a few hundred bytes to a few kilobytes, so it is a rounding error next to the image itself. Removing it is about privacy rather than file size.