Literally thousands of viruses exist, so it would be impossible to name them all right here. The most common virus is the common cold, called rhinovirus. You will know if you have it because you will have a runny nose and tired feeling. Some other viruses include influenza a and b. Symptoms are similar plus sometimes fever and aches.
Viruses include HIV, (AIDs,) flu, the common cold, herpes simplex, (cold sores,) smallpox, and multiple sclerosis to name a few. Some require testing to know if you have had them.
