What is water of crystallisation? Write the common name and chemical formula

What is water of crystallisation? Write the common name and chemical formula of a commercially important compound which has ten water molecules as water of crystallisation. How is this compound obtained? Write the chemical equation also, list any two uses of this compound.

Water of crystallisation :
Na2C03 10H2Ois hydrated sodium carbonate salt or sodium carbonate with water of crystallisation. Na2C03 is anhydrous sodium carbonate or salt of sodium carbonate (anhydrous) and 10H2O means water of crystallisation. It impacts on the colour and shape of the crystals.
Preparation

Uses
(i) Used in glass, soap and paper industries.
(ii) Used for removing permanent hardness of water.