Actually depreciation is the amount we charge on asset for their usage. Actually it is expenses which i have paid already by buying fixed asset and consuming it over a period. So what ever the cost which i consumed should go to reduce the asset value because the asset is no more valued at their purchase cost. But i don't exact what was the cost i consumed during the period. So when we don't know its exact quantum we create provision.
But in financial statement we will show it as
Gross Block of asset : Cost of the asset
Less : Depreciation block : Provision for depreciation
Net block: : WDV.