Question

study of writing on hard surfaces

Answer 1

inscriptions are writings engraved on hard surfaces like metal, rock, stone. The study of inscriptions is called epigraphy. Inscriptions were mainly made on faces of cliffs, on stone pillars, inside caves and on rock. Inscriptions are important source of information of India's past.
Ex: inscriptions belonging to Chanukya period have been found at Aihole Pattadakal, Karnataka

Answer 2

Writing on hard surfaces is known as engraving inscriptions and the study of inscriptions is called epigraphy. Epigraphy is an important source to study the medieval history.