Finance is the application of the principles of financial economics to an inter-related set of monetary problems. In the case of a company, this generally involves balancing risk and profitability and is typically called managerial finance or corporate finance. Investment theory is concerned with the identification of an optimal portfolio of assets, given a set of objectives and constraints, as well as with the valuation of assets. Finance can also be used by individuals (called personal finance), and by governments (called public finance).