Ghaib refers to everything which is hidden or unseen. Anything that is hidden and cannot be seen or sensed or understood by human intellect or knowledge is Ghaib. In Islam, Muslims are obligated to have Eman-bil-Ghaib (faith in the unseen). As per the Holy Quran, only Allah knows the Ghaib of the Universe and everything beyond it, and Only He provides this information to his selected (Prophets) people via revelation or other means.