Hi
It's great that you haven't had to resort to techniques such as this one. It is only meant for babies who have real trouble learning to comfort themselves to sleep and cry for long periods every night. That's why I consider it a last resort and wondered if others agree.
The ferber technique was invented by Dr Richard Ferber in 1985. Since then it has taken on many names such as, cry it out, self-soothing, sleep training, crying down and many more. Some techniques vary slightly in the details but they all work along the same basic principal as Ferber first proposed.
The basic idea is to leave baby to cry for a small duration of time before going into check on him. This length of time gradually increases every night until the baby learns to comfort himself back to sleep without screaming the house down!