What is meant by ‘dehydrating agent?

What is meant by ‘dehydrating agent? Describe with a chemical equation, an activity to show that concentrated sulphuric acid is a strong dehydrating agent.

A substance which can remove water from other substances is known as dehydrating agent. On treating sugar with concentrated sulphuric acid, it dehydrates into black mass of carbon called sugar charcoal. This is known as charring of sugar. Here, sulphuric acid removes hydrogen and oxygen atoms of sugar in the form of water molecules.