viral

Viral describes anything related to a virus, an infectious agent that replicates inside the cells of living hosts. In biology, viruses are submicroscopic particles composed of nucleic acid (RNA or DNA) enclosed in a protein coat; many have a lipid envelope. Viruses are obligate intracellular parasites, meaning they cannot reproduce outside a host cell, and their replication can cause disease.

Virions, the complete viral particles, can have various structures and genome types. They enter cells by binding to receptors, release their genome, hijack cellular machinery to replicate, assemble new virions, and exit to infect others. Viruses are classified by genome type (DNA or RNA), strandedness, and replication strategy, a framework known as Baltimore classification.

In health contexts, viral infections range from mild to life-threatening. Transmission occurs via respiratory droplets, bodily fluids, vectors, or direct contact. Prevention relies on vaccination, hygiene, and vector control; treatment often includes antivirals or supportive care. Public health measures monitor outbreaks using metrics such as the basic reproduction number (R0) and viral load to assess infection levels.

In popular culture, viral describes content that spreads rapidly online through social sharing, such as viral videos or memes. The term is a metaphor drawn from the rapid, exponential replication of viruses and does not imply any biological properties of the content.

Etymology: viral derives from virus, Latin for poison; in modern usage it encompasses both scientific contexts and metaphorical uses in digital culture.