Viral vectors are tools used in gene therapy to deliver genetic material into cells. They are modified viruses that have been engineered to be safe and non-infectious. By using these vectors, scientists can introduce new genes into a patient's cells, potentially correcting genetic disorders or enhancing immune responses against diseases. These vectors can come from various types of viruses, such as adenoviruses or lentiviruses, which have natural abilities to enter cells. The use of viral vectors is a promising area of research in medicine, particularly for treating conditions like cancer and inherited genetic diseases.