What does intrinsic lock actually mean for a Java class?

Question

In order to properly understand the issues and solutions for concurrency in Java, I was going through the official Java tutorial. In one of the pages they defined Intrin

Answer 1

Locks can be divided in two classes - 'reentrant' and 'not reentrant'. In Java 'synchronized', base implementation of interface Lock (class ReentrantLock), interface ReadWriteLock (class ReentrantReadWriteLock) - are reentrant. Reentrancy means - one thread can again and again hold the lock.