Coronavirus is a large family of viruses that cause illnesses

Coronavirus is a large family of viruses that cause illnesses ranging from the common cold to more severe infections such as pneumonia, Middle East Respiratory Syndrome and severe acute respiratory syndrome.

The name “coronavirus” is derived from the Latin corona and the Greek κορώνη (korṓnē, “garland, wreath”), meaning crown or halo. This is the characteristic of the virion when seen under an electron microscope.

Coronaviridae Members of the genus Coronavirus also contribute to respiratory illness, including severe disease.

Coronaviruses cause about 1/3 of common colds and SARS.
Strains of coronavirus
There exist seven strains of the virus that have been identified.

Human coronavirus OC43 (HCoV-OC43)
Human coronavirus 229E (HCoV-229E)
Human coronavirus NL63 (HCoV-NL63)-New haven coronavirus
Human coronavirus HKU1
Middle East Respiratory Syndrome (MERS-CoV)-Novel coronavirus, 2012 and HCoV-EMC
Novel coronavirus (2019-nCoV) Wuhan pneumonia or Wuhan coronavirus
Novel means newly discovered. It is used as a placeholder name to refer to a newly originated of discovered virus.

A novel coronavirus (nCoV) is a new strain that has not been previously identified in humans.

Signs and symptoms
Coronaviruses cause respiratory and enteric infections in humans.

The major site for viral replication is the epithelial cells of the respiratory tract.

The common severe symptoms are;

High fever of 100.4 degrees F or higher
Kidney failure and death
Infected patients also present with;

General body aches
Mild breathing difficulties at the onset
Dry cough after 2-7 days
Runny nose
Gastrointestinal disturbances
These symptoms may last for about 7 days with variations in different victims. More often there are no symptoms but the patient still sheds infectious viruses

PS: Learn more about the severe infections caused by coronaviruses:

Middle East Respiratory Syndrome and Severe acute respiratory syndrome.