What is volatile modifier in java?

Ans                
Volatile is the modifier applicable only for variables &we can’t apply or class & methods. If the value of the variable keep on change such type of variable we have declare with volatile modifier. If declare as volatile for every thread a separate local copy will be created. Once the value get finalized just before terminating the thread the master copy value will be updated with local stable value.
The main disadvantage of volatile keyword is creating and maintaining a separate copy for every method.
Volatile variable means it’s value keep on change, but final value can’t change the value, combination of volatile & final is illegal for all variables.