X-rays and metal detectors are used to control what is allowed to pass through an airport security perimeter

Security spikes protect a gated community in the East End of London

Security means to prevent dangers or losses. In general, security is similar to safety. The difference between the two is that security cares more than general safety about dangers from the outside.

Airports and banks usually have a lot of security measures. Prison security is used mainly to stop prisoners from escaping. It is also used to stop prisoners from harming prison employees or other prisoners.