Antigen tests are diagnostic tools used to detect specific proteins, known as antigens, from pathogens like viruses. They are commonly used for rapid testing, especially for illnesses such as COVID-19. These tests provide quick results, often within 15 to 30 minutes, making them useful for screening in various settings. The process typically involves taking a sample, usually from the nose or throat, and applying it to a test device. If the antigens are present, a visible line appears, indicating a positive result. Antigen tests are generally less sensitive than PCR tests, but they are valuable for their speed and ease of use.