Influenza viruses are mainly spread from person to person through droplets produced while coughing or sneezing. They can also be transmitted by indirect contact by touching a contaminated object or surface and then touching your own mouth, eyes or nose before washing your hands. This is also called fomite transmission.
Different viruses can survive on surfaces for different lengths of time but generally for longer on hard, impermeable surfaces than on porous surfaces. Influenza and cold viruses can still be infective for two hours and maybe up to eight hours. It is easier to catch the common cold than influenza by fomite transmission because some of the cold viruses have much smaller infectious doses than the influenza virus.
Some diseases may be mainly spread via fomite transmission. Examples being cold sores, conjunctivitis, meningitis, strep infections and possibly the common cold itself.