The study examines the three most influential international rating agencies (Standard and Poor's, Moody's and Fitch Rating), their role and importance in the financial markets, credit assessment methodology, credit rating development and credit rating procedures, as well as the impact of credit rating agencies and their ratings on the economies of different countries before and after the global financial and economic crisis. Also, two important questions about the "Big Three" have been discussed: "Do they provide adequate information to investors or a sense of confidence in the future?" and "Is there a political influence on them in determining the credit rating?".