https://en.wikipedia.org/wiki/Virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.

https://www.britannica.com/science/virus
Learn about the history, classification, and characteristics of viruses, the smallest infectious agents that can replicate only in living cells. Explore how viruses cause diseases, how they are studied, and how they may have ecological significance.

https://my.clevelandclinic.org/health/body/24861-virus
Learn what viruses are, how they infect hosts and cause diseases, and what types of viruses exist. Find out how viruses reproduce, how they are classified and how they can be treated.

https://www.khanacademy.org/science/biology/biology-of-viruses/virus-biology/a/intro-to-viruses
Learn what a virus is, how it infects a cell, and how it differs from bacteria. Explore the structure, diversity, and evolution of viruses with examples and diagrams.

https://www.medicalnewstoday.com/articles/158179
Learn what viruses are, how they reproduce, and how they can cause illness in humans and other living organisms. Find out about different types of viruses, such as coronaviruses, and how they spread and change over time.

https://www.nationalgeographic.org/encyclopedia/viruses/
Learn about viruses, their structure, replication, and effects on living hosts. Find out how viruses can be used for gene therapy and how they differ from bacteria.

https://www.verywellhealth.com/viruses-7106426
Learn what viruses are, how they work, and how they can make you sick. Find out the common ways to transmit and prevent viral infections, and the best treatments for different types of viruses.

https://www.who.int/health-topics/coronavirus
Coronavirus disease (COVID-19) Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus. Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment. However, some will become seriously ill and require medical attention.

https://en.wikipedia.org/wiki/Viral_disease
Viral disease. A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells. [1] Examples are the common cold, gastroenteritis and pneumonia. [2]

https://www.nationalgeographic.com/science/article/viruses/
Learn about the history, structure, and diversity of viruses, the tiny microbes that infect and replicate within cells. Find out how viruses spread, cause diseases, and may have helped life evolve.

https://www.britannica.com/summary/virus
Learn about the structure and features of viruses, the microscopic, simple infectious agents that can multiply only in living cells of animals, plants, or bacteria. Find out how viruses cause diseases, how they are classified, and how they are treated or prevented.

https://www.sciencealert.com/virus
A virus is a genetic material contained within an organic particle that invades living cells and uses their host's metabolic processes to produce a new generation of viral particles. Learn about the types, sizes, and complexities of viruses, as well as their role in the natural world and the debate over their status as living or non-living.

https://biologydictionary.net/virus/
Learn what a virus is, how it replicates, and how it infects different hosts. Explore the different types of viruses, their structures, and their effects on living organisms.

https://www.khanacademy.org/science/biology/biology-of-viruses
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https://theconversation.com/what-is-a-virus-how-do-they-spread-how-do-they-make-us-sick-133437
Learn about the basics of viruses, their structure, life cycle, types and impact on humans and other organisms. Find out how COVID-19, a coronavirus, is different from the flu and how to prevent its spread.

https://my.clevelandclinic.org/health/diseases/24473-viral-infection
Learn about viral infections, the common and serious diseases you get from viruses that use your cells to reproduce. Find out the types, symptoms, causes, diagnosis and treatment of viral infections, from colds and flu to COVID-19 and Ebola.

https://www.nature.com/scitable/definition/virus-308/
Learn what a virus is, how it infects a host, and how it replicates within the host cell. Explore the diversity, function, and role of viruses in human and animal health, and the challenges of viral infections and prevention.

https://www.genome.gov/genetics-glossary/Virus
A virus is an infectious microbe consisting of a segment of nucleic acid (either DNA or RNA) surrounded by a protein coat. A virus cannot replicate alone; instead, it must infect cells and use components of the host cell to make copies of itself. Often, a virus ends up killing the host cell in the process, causing damage to the host organism.

https://www.virustotal.com/
VirusTotal is a free online service that scans files and URLs for malware, viruses, and other threats.

https://www.ncbi.nlm.nih.gov/books/NBK8174/
Viruses are small obligate intracellular parasites, which by definition contain either a RNA or DNA genome surrounded by a protective, virus-coded protein coat. Viruses may be viewed as mobile genetic elements, most probably of cellular origin and characterized by a long co-evolution of virus and host. For propagation viruses depend on specialized host cells supplying the complex metabolic and

https://www.livescience.com/53272-what-is-a-virus.html
A virus requires a host cell to replicate, or make more copies of itself, said Jaquelin Dudley, a professor of molecular biosciences at the University of Texas at Austin.

https://medlineplus.gov/viralinfections.html
Learn about viruses, the tiny germs that can infect human cells and cause disease. Find out how viruses are spread, how they cause symptoms, and how to prevent or treat them. Explore specific viruses, such as adenoviruses, enteroviruses, and HIV, and their related issues.

https://www.merriam-webster.com/dictionary/virus
Learn the origin, history, and usage of the word virus, a submicroscopic infectious agent that causes diseases in humans, animals, and plants. Find out the difference between virus and bacteria, virus and computer virus, and related terms such as filterable virus and trojan horse.