FLU viruses are made up of tiny particles which can spread through tiny droplets which come out of your nose and mouth when you cough or sneeze.
If you do not cover your mouth when coughing or sneezing the virus spreads when others inhale these droplets.
And if you cough or sneeze into your hand, those droplets and the germs in them are easily spread to any surfaces that you touch, where they can survive for some time.
Common surfaces where flu viruses can be found include door handles, computer keyboards, phones and remote controls
By touching these everyday items and then touching your face the virus can enter your system and that is how all cold and flu viruses, including swine, flu is passed from person to person.