What is the most common type of virus in the world?

There are many types of viruses that exist in the world, but the most common type is the bacteriophage, or phage for short. Phages are viruses that infect bacteria, and they are found everywhere that bacteria are present.

Phages are the most abundant biological entities on the planet, with an estimated 10^31 phages in the biosphere. They are incredibly diverse in terms of their structure, genome size, and replication strategies, which makes them very effective at infecting and killing bacterial cells.

While phages are not harmful to humans, they are incredibly important in regulating bacterial populations in the environment. They are also being studied as a potential alternative to antibiotics in the treatment of bacterial infections.