How does the automatic memory management mechanism behave if an object contains a reference to itself?

In C#, the automatic memory management mechanism (Garbage Collector, GC) is based on counting the reachability of objects from root references.

If an object contains a reference to itself (self-reference), it does not prevent the garbage collector from freeing the memory if there are no external reachable references to that object. GC analyzes the object graph starting from root references and marks all reachable objects. Objects that are only reachable through cyclic references (including self-references), but are not reachable from roots, are considered unreachable and are subject to collection.

Thus, a self-reference does not prevent the collection of an object if it is not used in the program.

Example:

class Node {
    public Node SelfReference;
}

var node = new Node();
node.SelfReference = node;

// If after this, node is no longer used and there are no other references to it,
// GC will free the memory despite the self-reference.