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A method marked synchronized is synchronized on an instance of the containing class. Only one thread at a time can call that method per instance.

e.g. if m1 and m2 are instances of MyClass, and MyClass.syncedMethod() is synchronized, m1.syncedMethod() and m2.syncedMethod() can be called at the same time by two threads, but if a third thread tries to call either, it will be blocked.

A method marked static synchronized is synchronized on the class. Only one thread at a time can call that method, period.

Synchronization on static methods will acquire lock on Class object of the enclosing class. This means only one thread can call static synchronized methods regardless of number of instances of that class.

By using synchronized on static blocks, means the whole class instance will be synchronized. If we have called lock inside this synchronized method, then this particular thread will be permanently locked.