Quarantine is a public health practice that involves imposing separation and the restriction of movement on a person who may have a communicable disease. It is done to prevent the transmission of a contagious disease. A quarantine can also be imposed on someone who has been exposed to a contagious disease to determine if he will become ill.
In Our Own Words
While isolation involves separating someone who has a contagious illness from others, quarantine restricts the movement of people who are not ill but perhaps have been exposed. It is done in order to prevent the spread of a contagious disease. An individual or group that was exposed to a contagious disease, but is not yet sick may be quarantined. The quarantine is in effect to determine if illness develops. It is done as a precaution and can be useful in preventing the spread of serious public health threats.