Finance is the study of money and how it is used. Specifically, it deals with the questions of how an individual or company acquires the money needed - called capital in the company context - and how they then spend or invest that money. Finance is often split into three areas: personal finance, corporate finance and public finance. At the same time, "finance" is about the financial markets, i.e. the overall "system"  that allows the flow of money, via investments and other financial instruments, between and within these areas as facilitated by the financial services sector. A major focus within finance is thus investment management — called money management for individuals, and asset management for institutions — and finance then includes the associated securities trading, investment banking, financial engineering and risk management.
More abstractly, "finance" is concerned with the investment and deployment of assets and liabilities over "space and time": i.e. it is about performing valuation and asset allocation today, based on risk and uncertainty re future outcomes, incorporating the time value of money (where the risk-appropriate discount rate is determined via an asset pricing model). As an academic field, finance theory is studied and developed within the disciplines of management, (financial) economics and applied mathematics. As the debate to whether finance is an art or a science is still open, there have been recent efforts to organize a list of unsolved problems in finance.