A financial system allows the exchange of funds between lenders, investors, and borrowers. It consists of complex, closely related services, markets, and institutions to efficiently link investors and depositors. There are various sources of funding for entrepreneurs and businesses according to the period of requirement (short, medium, or long term), purpose (fixed assets vs working capital), and nature (debt vs equity). Internal sources include retained profits and owner's savings, while external sources comprise loans, trade credit, venture capital, and financing from banks and financial institutions.