Flu (influenza) is a common infectious viral illness spread by coughs and sneezes. It can be very unpleasant, but you’ll usually begin to feel better within about a week.
You can catch flu all year round, but it’s especially common in winter, which is why it’s also known as seasonal flu.
Flu isn’t the same as the common cold. Flu is caused by a different group of viruses and the symptoms tend to start more suddenly, be more severe and last longer.