Why does an object property expand to infinity in debugging? and what does base mean?

Question

ASP.NET

Good afternoon! I am learning MVC. Actually the whole point of the question in the picture, why is this happening? I regularly see this in debug mode. when hovering the mouse pointer over a variable, some of its properties can be "expanded" indefinitely.
And the second question, what does the "base" property mean?
And I will be grateful for a tip where you can read about all these properties (like base)

Answer 1

base