Answer:
Depreciation is the process to allocating an asset's cost as an expense over its useful life.
Step-by-step explanation:
An asset's cost price is not expended fully in the year it is purchased as revenue generated from the asset is for many years. A such, asset's cost is allocated through it's useful life. Also, a part of it is expensed in the form of depreciation every year.
It is not a process of valuation, it is a process of cost allocation.
Depreciation can be calculated using straight line method, written down value method, MACRS etc.