What is garbage collection in Java?
Why Interviewers Ask This
Foundational questions like this help interviewers calibrate the rest of the interview. A confident, accurate answer signals that you have solid Java basics — a prerequisite for any developer role.
Answer
Garbage collection (GC) is Java's automatic memory management mechanism that reclaims memory occupied by objects that are no longer reachable by any live reference in the program. Developers do not manually free memory (unlike C/C++), which eliminates memory leaks from forgetting to deallocate and dangling pointer errors. The JVM's garbage collector runs in the background, periodically identifying unreachable objects and freeing their memory. The primary GC regions are the heap (where objects live) and its generations: Young Generation (Eden + Survivors) and Old Generation. You cannot force GC, but System.gc() suggests it (the JVM may ignore it).
Common Mistake
A common mistake is memorizing definitions without understanding implications. When asked this question, go one level deeper — explain what happens when this concept is misused or ignored.
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