Present is the most real perception of time however almost all of what we perceive as the present is already past. The present is a fleeting moment; whatever is happening now (present) is confined to an infinitesimally narrow point on the time line which is being encroached upon by what we think of as the past and the future. Present may be mental awareness of the recording of memory into our brain. A person can go to an event but fall asleep and miss the event completely, so that event basically does not exist in his past. Unless we are consciously aware of an event it does not enter our past memory. Events which we do not directly perceive are part of other people’s memories or other recording devices like books videos. Weathering effect on aging buildings or rocks is another form of natural recording.
Internet Encyclopedia of Philosophy