H1N1, also known as the swine flu, is a type of influenza virus that first emerged in 2009. It is called "swine flu" because it was initially found in pigs, but it can spread from person to person. Symptoms of H1N1 are similar to those of regular flu, including fever, cough, and body aches. Most people recover without needing special treatment, but some may experience severe illness. The H1N1 pandemic in 2009 led to widespread concern as the virus spread globally. Vaccines were developed to help protect against it, and public health measures were implemented to reduce transmission. Today, H1N1 is included in the seasonal flu vaccine, helping to keep communities safe.