non-compacting garbage collector(a type of garbage collector that does not move objects in memory once they are allocated. It simply marks objects that are no longer in use and recycles their memory space for future allocations Alex_Odeychuk)
compacting garbage collector(a type of garbage collector that moves objects in memory to eliminate fragmentation and make more efficient use of memory space. It relocates live objects so that they are contiguous in memory, leaving all the free space together in one block Alex_Odeychuk)
