In finance and accounting, capital generally refers to financial wealth, especially that used to start or maintain a business. It is assumed that other styles of capital, e.g. physical capital, can be acquired with money, so there is little need for any further analysis.
classical economics, capital is one of three factors of production, the others being land and labour. Goods with the following features are capital:
Investment in classical economic theory is the act of producing capital. In order to invest, goods must be produced which are not to be immediately consumed, but instead used to produce other goods as a means of production. Investment is closely related to saving.
human capital (or in more detailed analyses, building up individual capital using instructional capital, recognizing that both the individual and the instruction may benefit from the interaction).
Less controversial analyses break down each of the major factors of production as its own 'style' of capital, allowing for the capital appreciation and depreciation of each asset. Such analyses recognize four styles of capital, or in more detail, six:
More modern analyses differentiate the latter three and avoid the term "human" in part so that non-human instructional capital (e.g. software), non-human individual capital (e.g. orang-utans painting, or a race-winning horse, or prize stud bull), and the activities of government can be analyzed more exactly for performance, e.g. in a health observatory[?]. Although it is still possible to calculate the traditional "human capital" yield as payments (like salary), it is rarely or not used when discussing the process of planning investment: for this it is broken down into the more specific styles, which are distinct when one considers the means of identifying them, investing in, and exploiting them.
Another prompting for the more exact and deeper six-style analysis is that infrastructural capital has declined in financial value relative to human capital, and natural resources have become more scarce. Meanwhile, both human development and biodiversity have become a main priority of government in every developed nation.
In part as a result, separate literatures have developed to describe both natural capital and social capital. Such terms reflect a wide consensus that nature and society both function in such a similar manner as traditional industrial infrastructural capital, that it is entirely appropriate to refer to them as styles of capital in themselves. In particular, they can be used in the production of other goods, are not used up immediately in the process of production, and can be enhanced (if not created) by human effort.
There is also a literature of intellectual capital and intellectual property law. However, this increasingly distinguishes means of capital investment, and collection of potential rewards for patent (imitative or instructional capital), copyright (creative or individual capital), and trademark (social trust or social capital) instruments. Literature that makes these distinctions tends to parallel the six-style analysis, which explains why three distinct bodies of law would have evolved in the first place.
Some analysts, e.g. Baruch Lev[?], claim there are seven styles of capital. It is not clear how his analysis relates to that of human development theory, as it arises from management accounting practices. It is not very widely used, not at all outside the US, and is under some suspicion as it emerged during the dotcom boom and did not specifically claim that those companies were grossly overvalued or corrupt, as later events proved them to be. This has led to speculation that political capital, or political influence or corruption, is his actual seventh factor. This is probably oversimplified, but calls for comprehensive accounting reform have reached the highest levels in the US, particularly in the wake of major accounting scandals, so it is hard to wholly dismiss this concern.