In the past it was suggested that they should be physical photos, attached to plain A4 paper with tape/glue, and a caption for location/date is ok. But do note that this isn't actually required anymore.
What If i will be undergoing the new scanning process procedure in submitting the documents. Does it really needed to be in a photo paper? Because in one guide lines it said it has to be in an a4 size paper. My photos have time stamps on it.