An oncogenic virus is a type of virus that can lead to cancer in humans or animals. These viruses can alter the normal behavior of cells, causing them to grow uncontrollably. Some well-known oncogenic viruses include the human papillomavirus (HPV), which is linked to cervical cancer, and the hepatitis B virus (HBV), associated with liver cancer. Oncogenic viruses can integrate their genetic material into the host's DNA, disrupting normal cell functions. This process can result in mutations and the activation of oncogenes, which promote cell division. Understanding these viruses is crucial for developing vaccines and treatments to prevent virus-related cancers.