What your photos say behind your back
A photo from your phone typically embeds the GPS coordinates of where it was taken (often to a few meters), the exact date and time, your device make and model, and the camera settings used. Post it, e-mail it, or attach it to a listing, and anyone with a metadata viewer reads all of it. Most platforms strip metadata on upload — but not all, and forwarding a file directly preserves everything.
The classic cases: selling something from home, sharing apartment photos, posting from a location you would rather not disclose, or publishing screenshots from a work machine that tags software versions.