The BlackRock MuniYield Quality Fund Inc (MQY) is a mutual fund that focuses on investing in high-quality municipal bonds. These bonds are issued by state and local governments to fund public projects and services. The fund aims to provide investors with tax-free income by investing in a diversified portfolio of municipal bonds with strong credit ratings. Managed by BlackRock, one of the largest investment management firms in the world, this fund offers a low-risk investment option for those seeking tax-exempt income.