How does garbage collection in .NET work, and what three phases does a collection cycle go through?

The .NET garbage collector automatically reclaims memory occupied by objects no longer reachable by the application, removing the need for manual memory management -- a collection cycle generally proceeds through marking (scanning the object graph from GC roots to determine which objects are still reachable), sweeping (reclaiming the memory of unreachable objects), and compacting (moving surviving objects together to reduce fragmentation and keep allocation fast) -- this automation prevents most memory leaks but means the GC can introduce brief pauses, especially if an application allocates large numbers of short-lived objects.

public void ProcessOrders() {
    for (int i = 0; i < 100_000; i++) {
        var temp = new OrderDto(); // short-lived object, becomes eligible for GC almost immediately
        // process temp
    } // by the time this loop ends, most 'temp' instances are already unreachable garbage
}