Viruses are unique biological entities that have a number of unique characteristics that set them apart from other forms of life. Though most commonly known for their ability to cause disease, viruses are actually fascinating and peculiar organisms that are still only partially understood. Viruses are incredibly small, making them difficult to study and observe. Most viruses are composed of just a few components, such as a protein coat and a strand of genetic material. This small size is why some have speculated that viruses have their own independent origin from the rest of life, separate from bacteria and other forms of life. Unlike most known forms of life, viruses lack any type of internal metabolism. This makes them extremely efficient parasites, as they are able to hijack the machinery of the host cell to create more of themselves. In addition, viruses can sometimes evolve quickly, and some have even become resistant to certain drugs, making them especially problematic for medical treatments. Overall, viruses are fascinating organisms and have held a lot of mystery and wonder to biologists over the decades. Despite their ability to cause disease, they are incredibly resilient and their unique characteristics can provide insight into how other forms of life evolved and function.