As an expert in the field of finance, I would be happy to provide you with information on the main types of fixed income securities and how they work.

Fixed income securities are investments that provide a fixed or predictable stream of income to the investor. These investments typically pay interest or dividends at regular intervals, and are generally considered to be less risky than other types of investments, such as stocks. Here are the main types of fixed income securities:

1. Bonds: A bond is a type of debt security in which the investor loans money to an entity (such as a corporation or government) in exchange for a fixed rate of interest over a set period of time. At the end of the term, the investor receives the original principal amount back.
2. Treasury Bills: Treasury bills, or T-bills, are short-term government bonds with maturities ranging from a few days to one year. They are considered to be one of the safest investments available, as they are backed by the full faith and credit of the US government.
3. Certificates of Deposit: Certificates of Deposit, or CDs, are issued by banks and typically offer a fixed rate of return over a set period of time. They are considered to be safe investments, as they are insured by the Federal Deposit Insurance Corporation (FDIC).
4. Preferred Stock: Preferred stock is a type of stock that pays a fixed dividend to investors. Preferred stockholders have a higher claim on the company’s assets and earnings than common stockholders, but typically do not have voting rights.
5. Corporate Bonds: Corporate bonds are similar to government bonds, but are issued by corporations. They generally offer higher yields than government bonds, but are also considered to be more risky.

In general, fixed income securities are a good option for investors who are looking for steady income and are willing to accept a lower rate of return in exchange for lower risk. By diversifying your investments across different types of fixed income securities, you can potentially minimize your risk and maximize your returns over the long term.