Azidothymidine, commonly known as AZT, is an antiviral medication primarily used to treat HIV infection. It works by inhibiting the reverse transcriptase enzyme, which is essential for the replication of the virus. By blocking this enzyme, AZT helps reduce the viral load in the body, allowing the immune system to recover and function more effectively. AZT was the first drug approved for the treatment of HIV/AIDS in the late 1980s and has played a significant role in improving the quality of life for many patients. While it can have side effects, its use has paved the way for the development of more advanced antiretroviral therapies.