Depreciation refers to two very different but related concepts:

The former affects values of businesses and entities. The latter affects net income. Generally the cost is allocated, as depreciation expense, among the periods in which the asset is expected to be used. Such expense is recognized by businesses for financial reporting and tax purposes. Methods of computing depreciation may vary by asset for the same business. Methods and lives may be specified in accounting and/or tax rules in a country. Several standard methods of computing depreciation expense may be used, including fixed percentage, straight line, and declining balance methods. Depreciation expense generally begins when the asset is placed in service. Example: a depreciation expense of 100 per year for 5 years may be recognized for an asset costing 500.

In determining the profits (net income) from an activity, the receipts from the activity must be reduced by appropriate costs. One such cost is the cost of assets used but not currently consumed in the activity. Such costs must be allocated to the period of use. The cost of an asset so allocated is the difference between the amount paid for the asset and the amount expected to be received upon its disposition. Depreciation is any method of allocating such net cost to those periods expected to benefit from use of the asset. The asset is referred to as a depreciable asset. Depreciation is a method of allocation, not valuation.