 Fixed capital is a concept in economics and accounting, first theoretically analyzed in some depth by the economist David Ricardo. It refers to any kind of real or physical capital fixed asset that is not used up in the production of a product. It contrasts with circulating capital such as raw materials, operating expenses and the like. So fixed capital is that portion of the total capital outlay that is invested in fixed assets such as land, buildings, vehicles, plan and equipment that stay in the business almost permanently or at the very least, for more than one accounting period. Fixed assets can be purchased via business, in which case the business owns them. They can also be leased, hired or rented, if that is cheaper or more convenient, or if owning a fixed asset is practically impossible for legal or technical reasons. Refining the classical distinction between fixed and circulating capital in DOS capital, Karl Marx emphasizes that the distinction is really purely relative, idiot refers only to the comparative rotation speeds turn over time of different types of physical capital assets. Fixed capital also circulates except that the circulation time is much longer, because a fixed asset may be held for 5, 10 or 20 years before it has yielded its value and is discarded for its salvaged value. A fixed asset may also be resold and reused, which often happens with vehicles and planes. In national accounts, fixed capital is conventionally defined as the stock of tangible, durable fixed assets owned or used by resident enterprises for more than one year. This includes plant, machinery, vehicles and equipment, installations and physical infrastructures, the value of land improvements, and buildings. The European system of national and regional accounts ESA 95 explicitly includes produced intangible assets e.g. mineral exploitation, computer software, copyright protected entertainment, literary and artistic originals within the definition of fixed assets. Land itself is not included in the statistical concept of fixed capital, even though it is a fixed asset. The main reason is that land is not regarded as a product to reproducible good. But the value of land improvements is included in the statistical concept of fixed capital, being regarded as the creation of value added through production.