Photos from phones and cameras carry hidden metadata (EXIF): the camera model, settings, the exact time – and often the GPS coordinates of where it was taken. Remove it before posting online. JPGs are cleaned without re-compressing, so quality is untouched.
Questions
Do social networks remove EXIF?
Most big ones do, but email, cloud links, forums and messaging apps often keep it.
Does removing metadata change the picture?
No. For JPG and PNG only the metadata blocks are removed; the image data is untouched.