Illness can be poor health for any one of many different reasons. If you are ill you may have an infection, a disease, or just generally feel unwell. There are many humorous illness quotes that attempt to look on the bright side no matter what is making you ill. If you develop an illness you may have a variety of symptoms, some that may be mild and others that can be more severe. The common cold is an illness, and so is the flu. Strep throat is another illness but this one is caused by bacteria and not a virus. Sometimes you may have severe illness that becomes life threatening, and if this happens you should always seek immediate medical attention from the nearest emergency room.