Explain how garbage collection works in Java. Discuss the different types of garbage collectors available, and explain the differences between them. How does the garbage collector determine which objects are eligible for collection?

Garbage collection in Java is the process of automatically identifying and disposing of objects that are no longer needed by the application to free memory. The main types of garbage collectors include Serial, Parallel, CMS (Concurrent Mark-Sweep), and G1 (Garbage-First). The system uses reference counting and reachability analysis to determine if an object is still in use. If there are no references to an object, it is considered eligible for garbage collection. Each garbage collector has its own pros and cons concerning pause time and throughput.