Flu is short for influenza, a very contagious viral infection that attacks your respiratory system, i.e. your nose, throat, and lungs.
After a few days of bed rest, the flu will most likely resolve on its own.
The flu is easily spread by the respiratory droplets of an infected person and can be transmitted from coughing, talking, or by physical contact such as shaking hands.
If you touch your nose, mouth, or eyes with unwashed hands, you could be putting yourself at risk, which is why hand hygiene is so important.