When depreciation expense is a debited, the corresponding account we credit is called accumulated depreciation. Accumulated depreciation is a contra account. It offsets the corresponding asset account. By using a contra account, the historical costs of the asset is not affected but at the same time we are able to reduce the value  of the depreciated asset with the accumulated depreciation account.

The journal entry to recognize depreciation is as follows:

Debit Depreciation expense

Credit Accumulated depreciation expense