There are two definitions in economics. # The capital of a firm, after deducting any liabilities to outsiders other than shareholders, who are typically the legal owners of the firm’s equity. This ownership right is the reason shares are also known as equities. # Fairness. Dividing up the economic pie. Economists have been particularly interested in this with regard to how systems of taxation work. They have examined whether taxes treat fairly people with the same ability to pay (horizontal equity) and people with different abilities to pay (vertical equity). The fairness of other aspects of how the gains from economic activity are distributed through society have also been debated by economists, especially those interested in welfare economics. Some economists start with the presumption that the free-market outcome is inherently inequitable, and that equity (sharing out the pie) must be traded off against efficiency (maximizing the size of the pie). Others argue that it is inequitable to take money away from someone who has created economic value to give to people who have been less skilled or industrious.