What is the definition of A Rating?

A rating is an assessment of credit-worthiness assigned to a bond, corporation or country. The idea behind a rating is that it gives investors an idea of how likely an entity is to repay its debts.

The ratings are assigned by a rating's agency, with the most famous being Moody's and Standard & Poors and typically follow a letter system with AAA being the top rating. As of October 2011, some AAA-rated countries are the United Kingdom, Germany, Hong Kong and Switzerland.