Infectious diseases are illnesses caused by pathogenic organisms such as bacteria, viruses, fungi, or parasites. These organisms can be spread directly or indirectly between individuals, often through contact with bodily fluids or contaminated surfaces. Infectious diseases can range from common ailments like the flu or strep throat to more serious conditions like tuberculosis or HIV/AIDS. Research in this area focuses on understanding how these pathogens spread, how they interact with the immune system, and developing treatments and prevention strategies to combat these diseases. This research is crucial for controlling outbreaks, developing vaccines, and improving public health.