What it is
A photo file may contain metadata describing when and where it was captured. Location coordinates are separate from the visible pixels. A blank wall in the picture can still be associated with a home address when the receiving app preserves that metadata. Other fields may include device and time information.
A useful example
You send a photo of a new computer from home. A recipient downloads the original and opens its information panel, which shows a map location. Cropping the picture would not necessarily remove metadata. Conversely, removing the coordinates would not conceal an address visible on a package label in the frame.
What to do
Inspect the actual file before sending it through the chosen app. On iPhone, Apple documents a share-sheet
Options → Location switch as well as
Adjust Location → No Location in Photos; the two actions serve different purposes. Its
photo-location guide gives the steps. You cannot retract a copy already downloaded by someone else, so use the check before sharing a sensitive original.
