Photo metadata is information stored alongside an image file. It is not printed into the picture, but apps can read it when you upload or send the file.
EXIF
EXIF is the camera record. It can include the time a photo was taken, the phone or camera model, lens settings, and sometimes GPS coordinates.
IPTC
IPTC fields are often used by photographers, publishers, and newsrooms for captions, authorship, copyright, and other editorial notes.
XMP
XMP is a flexible format used by editing software. It may name an application, preserve edit history, or carry a sidecar note.
None of these tags changes the visible pixels. If you are not sure what a file contains, inspect it first and clean a copy before sharing.