A feeling of alarm caused by the expectation of danger, pain, disaster or other calamities, fear may lead to aggression and violence including war and conflict of all kinds. It may also lead to discrimination, conformism, inertia, alienation, delusion, dependency, lack of participation, corruption, injustice and inequality. Fear may exist in the form of general anxiety which has no object. Fear may also be phobic, that is, very specific to a particular object, condition, environment, etc, such as claustrophobia. Fear of grievous physical injury or death in the face of a real threat may cause tremor, sweating, heart palpitation, and involuntary passing of urine or faeces. Fear itself can be a cause of death, by shock or heart attack. Fear can grip whole armies or civilian populations.
The hallmarks of sudden fear and anxiety are the same: fear as opposed to anxiety is a rational reaction justified by circumstances, whereas anxiety is to a greater or lesser extent irrational.