There are two ways in which securities are issued. They are either issued and interest is earned on the principal, hence the term interest-based securities, or they can be issued at a discount or at a premium, hence the term discount based securities.
In this post I am going to talk about those securities that are interest-based.
When you talk about such securities the investor, you, will invest a certain amount of money called the principal. This is the amount that you would invest at the beginning of the contract and at maturity you will receive this same amount.
Then the return every year on this amount that is invested is called the interest. The interest earned will be calculated using the interest rate on the investment. The higher the interest rate the higher the interest earned.
Hence generally this principal is invested for a length of time ranging from 7 days to five years. The interest rate of the investment also depend on the length of time for which the principal is invested. Generally the longer the time the higher the interest rate. This is because your money is locked in the investment for a longer length of time. You will thus have to be compensated for the decrease liquidity and the greater risk taken.
Now there are two ways in which interest will be accrued on the principal. It will be either a simple interest whereby the interest will be calculated every year on the principal alone. Hence you will obtain the same interest every year.
You can read a post on simple interest here.
The other type of interest is the compound interest whereby the interest earned every year is calculated on the principal and the interest earned in previous years. You can read a post on compound interest here.