Java Memory Management, with its built-in garbage collection, is one of the language’s finest achievements. It allows developers to create new objects without worrying explicitly about memory allocation and deallocation, because the garbage collector automatically reclaims memory for reuse. This enables faster development with less boilerplate code, while eliminating memory leaks and other memory-related problems. At least in theory. When an object is no longer used, the garbage collector reclaims the underlying memory and reuses it for future object allocation. This means there is no explicit deletion and no memory is given back to the operating system. To determine which objects are no longer in use, the JVM intermittently runs what is very aptly called a mark-and-sweep algorithm. As you might intuit, it’s a straightforward, two-step process: The algorithm traverses all object references, starting with the GC roots, and marks every object found as alive. All of the heap memory that is not occupied by marked objects is reclaimed. It is simply marked as free, essentially swept free of unused objects.