Depreciation is a form of an allowance for the wear and tear (exhaustion) of property used in a trade or a commercial enterprise. The idea is to match as well as possible the actual use (utility) of the asset to its change or reduction in fair market value due to that utility.
Accumulated depreciation is the amount identified on the balance sheet as an offset account against the corresponding fixed assets. Accumulated depreciation is the lifetime accumulated amount taken as a deduction on the income statement (profit and loss).
When a small business purchases fixed assets two financially based opposing forces come into play. The first is the financial reporting desire to present information in a fair manner so management can make good financial decisions. The opposing force has to do with taxation. Here the business desires to report less profit to reduce the tax obligation.
The balance sheet serves as an historical report. It identifies the accumulated change in value since inception. The balance sheet is organized into two halves and both sides must be equal in value. In addition, the balance sheet is a snapshot of the financial condition at a single moment in time along the lifetime timeline of the company.