The common cold is probably the most common respiratory (breathing) disease. Many different viruses can cause a cold; over a hundred cold viruses (rhinoviruses) have been identified so far.
How do you catch a cold?
Cold viruses are very contagious — it's easy to catch them from other people. When someone has a cold, there is a lot of the cold-causing virus in their nose and throat. If the person coughs or sneezes, they can spray the virus into the air and infect other people directly. If the person with the cold coughs or sneezes on objects, or on their hands, those things can carry the virus too. Cold viruses can live for many hours on objects like toys, door handles, telephones, pens, tissues and more. If a healthy person picks up an object covered with cold germs, then touches their nose, mouth or eyes, they can catch the virus.
Cold viruses are around all year long, but we seem to get more colds in the winter. This is because we spend more time indoors in the winter, so we're in closer proximity to other people and to their germs.
If you are tired, in poor physical condition, exposed to some air pollutants or have a chronic lung disease like asthma or COPD, you may get colds easier.