The current COVID-19 pandemic shows how little many people know about viruses. Yet apart from COVID-19, the world has observed epidemic spread of another SARS virus, of the Ebola virus, and of the Zika virus during the last two decades. The human immunodeficiency virus (HIV) is still one of the most dangerous viruses worldwide. Some types of the human papillomavirus (HPV) are the main cause of cervical cancer. Cases of measles, also caused by a virus, increase in numbers due to lack of access to or refusal of vaccination. Furthermore, there is the widespread belief that viruses are similar to bacteria and may thus be fought off with antibiotics. Yet viruses have no metabolism. Thus, antibiotics cannot work against them, but may instead cause more harm than help, given side effects such as killing beneficial bacteria (e.g., in the intestine). Second, misuse of antibiotics is one key factor in the evolution of antibiotic-resistant bacterial strains -- a strong public health issue nowadays. This article informs readers what viruses are, how they are distinct from bacteria, how they may have evolved, and how diseases they cause may be prevented. Additionally, insights from studies concerning students' virus-related knowledge are summarized.