A cold is an upper respiratory tract infection (affecting the nose, nasal airways and throat), caused by a virus. The virus can be spread through direct contact: by breathing in contaminated droplets or touching hands with someone who already has a cold; or indirectly, by touching a contaminated object for example. Colds can thus be spread all year round, and not just at wintertime.
To avoid catching one, wash your hands at regular intervals, keep antibacterial hand gel or soap on you and wear a mask if travelling on public transport.
The aim is to keep the virus away from your face!