The H1N1 virus, also known as the swine flu, is a type of influenza virus that can infect both humans and animals. It was first identified in 2009 during a global outbreak and is known for causing respiratory illness. The virus spreads through respiratory droplets when an infected person coughs or sneezes. Vaccines are available to help protect against the H1N1 virus, and public health measures, such as handwashing and wearing masks, can reduce transmission. Most people recover from the infection without needing medical treatment, but it can be more severe in certain groups, including young children, the elderly, and those with underlying health conditions.