Homonym: virus (Malware)
A virus is a tiny infectious agent that can only replicate inside the living cells of an organism. Unlike bacteria, viruses are not considered living things because they cannot reproduce on their own. They invade host cells and use the cell's machinery to make copies of themselves, which can then spread to other cells. Common examples of viruses include the influenza virus and the common cold virus.
Viruses can cause a variety of diseases in humans, animals, and plants. Some viruses lead to mild illnesses, while others can be severe or even life-threatening, such as the HIV virus or the COVID-19 virus. Vaccines and antiviral medications are important tools in preventing and treating viral infections.