Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Fever ?
    ### Response:
    A fever is a body temperature that is higher than normal. It is not an illness. It is part of your body's defense against infection. Most bacteria and viruses that cause infections do well at the body's normal temperature (98.6 F). A slight fever can make it harder for them to survive.
    