An intangible asset is an asset that lacks physical substance (unlike physical assets such as machinery and buildings) and usually is very hard to evaluate. It includes patents, copyrights, franchises, goodwill, trademarks, and trade names, and the general interpretation also includes software and other intangible computer based assets. Contrary to other assets, intangible assets generally—though not necessarily—suffer from typical market failures of non-rivalry and non-excludability.