The document defines investment and discusses it from several perspectives. It is generally defined as applying money to earn more money in the future. In finance, investment refers to purchasing a financial product or asset to earn future returns. In business, it means purchasing physical goods like equipment to improve future operations. Economics views investment as utilizing resources today to increase income or output tomorrow. Real investments purchase physical capital while financial investments purchase contracts. The key aspects of investment discussed are risk, return, time horizon, liquidity, and types of financial assets.