What is hardness, and how is it generally tested?

(Apa itu keras dan bagaimana cara mengetesnya?)

answer & Explaination:

Hardness is a measure of a material's resistance to being scratched or dented and is measured using various experimental techniques, including the Vicker's and Knoop tests.

How do you test it? By touching the object and feel it. What did the object react to your touching? does it liquidy like water? Is it wet? Or is it dry and tough? If you hit the object but the object stay still, infact your hand hurt, that's hardness.

-nayya-