Credit ratings are issued by credit rating agencies and represent their opinion on the likelihood that a debtor will default on their debt obligations. The ratings are determined after evaluating factors such as the issuer's financial history and strength of assets. Common credit ratings use letter or number symbols to convey the agency's assessment of default risk, from AAA/Aaa (highest safety) to D (already in default). Credit ratings provide investors with an independent evaluation of risk to help inform their investment decisions.