What is an extension method?
IP addresses - Simple explanation
What is polymorphism?
What is the Liskov substitution principle? (Part 2)
What is the meaning of idempotency?
What is the Liskov substitution principle? (Part 1)
How to undo a rails generate command?
How it’s done
What is a class and what is an instance?
Using Linq to Filter Objects in your current space - (AutoCad .net API)
A brilliant example which I basically restructured from some code Gilles provided: