Investments allow individuals to generate returns from their savings by putting idle funds to use. There are three pillars of investment - safety, liquidity, and growth. People invest to earn returns, generate funds for goals, and prepare for the future like retirement or unexpected needs. Key rules for investors include starting early, investing for the long rather than short term, and investing regularly. The document provides an overview of investments, outlining what they are, reasons to invest, principles for investors, and factors to consider like investment options, liquidity, safety, returns, and asset allocation.