Serology testing is a laboratory method used to detect and measure the presence of antibodies in a person's blood. These antibodies are proteins produced by the immune system in response to infections, vaccines, or other foreign substances. By analyzing a blood sample, healthcare providers can determine if a person has been exposed to specific pathogens, such as viruses or bacteria. This type of testing is commonly used for diagnosing diseases like HIV, Hepatitis, and COVID-19. It can also help assess immunity after vaccination or previous infections. Serology tests are valuable tools in public health for tracking disease outbreaks and understanding population immunity.