Can you explain how garbage collection works in managed programming languages?

In managed programming languages such as Java or C#, Garbage Collection (GC) is an automatic process of freeing memory that is no longer used by the program.

The main idea: when objects in memory become unreachable (no references to them from active code), the garbage collector detects and frees the memory occupied by them.

Approximate working mechanism:

1. Reachability Tracking: GC starts with root objects (stack, static variables) and marks all objects that can be reached.
2. Garbage Identification: objects that are not marked are considered garbage.
3. Memory Freeing: memory occupied by garbage is released for reuse.

In Java, for example, there are several GC algorithms (Mark-and-Sweep, Generational GC) that optimize work in terms of time and memory.

Example code where an object becomes a candidate for garbage collection:

public class Example {
    public static void main(String[] args) {
        Object obj = new Object();
        obj = null; // now the object is unreachable and can be collected by GC
        System.gc(); // call to the garbage collector (does not guarantee immediate execution)
    }
}