Viral reactivation refers to the process by which a dormant virus becomes active again within a host cell. This can occur due to a variety of factors such as stress, immunosuppression, or changes in the host's environment. Viral reactivation can lead to the recurrence of symptoms or the development of new infections, and is a common phenomenon in many viral infections such as herpesviruses, HIV, and Epstein-Barr virus. Research in this area aims to understand the molecular mechanisms underlying viral reactivation, develop treatments to prevent or control reactivation, and improve our overall understanding of how viruses persist and reactivate within the host.