A lockdown is typically an event during which a place will be secured to ensure that no one is able to enter or leave without people in control of the location being aware of such movements. This is typically used in prisons and similar correctional facilities during emergency situations, to ensure that prisoners do not escape. The name of this type of event comes from the tendency of all of the cells and doors being locked to ensure security. A “lockdown” can also be a state in which other locations find themselves at heightened security.
There are a number of different ways in which a lockdown can occur and be ordered. One of the simplest forms of lockdown can occur in a prison or similar correctional facility. In this type of location, lockdowns are usually associated with prisoners attempting to escape or during emergency situations. To prevent escapes, or prisoners using an emergency as a distraction they could use to their advantage, prisoners are returned to their cells and all doors are locked and secured.
This is one of the most common usages of the term “lockdown,” though it can refer to heightened security in other settings as well. These alternative lockdowns can also live up to the name, and may involve doors being locked or otherwise monitored to ensure greater security. Some retail stores, for example, utilize a lockdown system in situations in which a child is reported as missing in the store. In order to better prevent kidnappings or children wandering away from these stores alone, once the employees of the store are notified a child is missing then all of the doors are monitored to ensure any children leaving the store are accompanied by a parent or guardian.
A lockdown can also be more metaphorical in nature, but still typically used in reference to a state of heightened security. This could refer to a country or city that is under martial law for some reason, and a location might not literally be locked, but travel though the area could be so closely monitored as to make it feel impenetrable. The term has also entered other forms of popular usage to refer to security, and a computer could be said to be in a state of lockdown if security was installed to prevent users from accessing the system from outside terminals.