Flu which is also commonly known as influenza is a contagious airborne viral infection that generally affects the respiratory system.

Influenza is highly contagious and spreads from one person to the other by direct contact of by inhaling airborne droplets of an infected person.

Common symptoms of flu include fever, cough, lethargy, joint pain, congestion, chills and headaches. Symptoms may be treated with over the counter medications or medications prescribed by a physician.

The causative agent for flu is the influenza virus. Influenza type A and type B virus are common causative agents of influenza in humans.

Flu or influenza and common cold are different infections which are caused by different viruses. However, some symptoms remain common which makes it difficult to differentiate between the two. Common cold has milder symptoms as compared to flu and generally does not cause any complications unlike influenza which could possibly develop into pneumonia or other infections.