Garbage Collector in Ruby is an automated memory management mechanism responsible for monitoring and freeing memory that is no longer used by the program. The GC ensures that memory allocated for objects that are no longer needed by the program can be reused, thereby optimizing system resources. Just imagine that there are objects in memory that are unnecessary. Their number keeps increasing. A memory leak occurs. The server may stop responding, and in the case of scaling, your costs will only increase. So, GC is needed for efficient use of RAM.

The Garbage Collector in Ruby works on the principle of "mark-and-sweep". The garbage collector traverses all objects that can be reached from root objects (such as local variables and global variables) and marks (mark) them as "reachable". After the marking process is complete, the collector moves to the sweeping phase (sweep), where it frees memory from all objects that were not marked. These objects are considered "unreachable" and their memory (the memory they previously occupied) can be reused.

Ruby also uses the concept of generations (Generational Garbage Collection or GGC), which involves dividing objects into generations based on their usage frequency, allowing for more efficient memory management by focusing the garbage collector's efforts on younger, more dynamic objects that change more frequently. GC is usually discussed when a Memory Leak occurs on the server. Of course, restarting the server will help for a while (RAM will be cleared and start filling up again), but this issue will still need to be addressed.