What are circular references? Explain how garbage collection deals with circular references?

Answer:

A circular reference is a series of references when a formula refers back to its own cell, either directly or indirectly and the last object references the first, resulting in a closed loop. Also it is a run-around where in two resources are interdependent on each other.

The methods to deal with circular references are:
• Weighted reference counting
• Indirect reference counting

There are some ways to handle problem of detecting and collecting circular references with the help of garbage collection.
• The system may explicitly forbid reference cycles.
• Systems ignore cycles if it have small amount of cyclic garbage.
• You can also periodically use a tracing garbage collector cycles.