Viral evolution refers to the process by which viruses change over time through genetic mutations and natural selection. These changes can occur rapidly due to the high replication rates of viruses, allowing them to adapt to new hosts or environments. This adaptability can lead to the emergence of new viral strains, which may have different characteristics, such as increased transmissibility or resistance to treatments. Understanding viral evolution is crucial for public health, as it helps scientists predict outbreaks and develop effective vaccines. For example, the evolution of the influenza virus necessitates annual updates to vaccines, while the emergence of new variants of SARS-CoV-2 has impacted global pandemic responses.