AAA rating is the highest rating for long-term bonds assigned by rating agencies by Standard and Poor’s (S&P). The rating is equivalent to Aaa by Moody’s. Examples of AAA-rated countries by S&P are Australia, Canada, Denmark, Germany, Liechtenstein, Luxembourg, Netherlands, Norway, Singapore, Sweden, and Switzerland.
AAA-rated companies or countries have the best creditworthiness compared to below-rated companies. Since having the strongest capacity to repay investors, they have low default risk, hence allowing them to borrow at a low-interest rate.
Lower risk means lower returns. Hence, while investors might not lose their money, they might not make much money.