What is Critical Chain method?

Let me start by asking you a question..

How many of you have told your team that the project duration is 90 days when the total days to complete the project duration signed off with customer was 100 days?
Most of you have done this!!
Having 10 days to be with you in order to handle any delay – is that correct? 
Giving incorrect information to your team – is that ethically wrong?
NO, Actually unknowingly you’ve implemented Critical Chain Method by inducing something called “Project Buffer”

Project Buffer:

It is the buffer which you’ve kept with you in order to absorb any delay without compromising on the project end date (those 10 days)
The yellow activities which you see depicts buffer. 
A critical chain uses buffers to absorb any delay on your project . 
To absorb overall delay in any path is Project Buffer (Buffer kept before the end of the project)

Feeding Buffer:

There would be times when you know that any task/activity given to a particular resource would take only X amount of hours/days. But you know the resource might be occupied e.g. Customer acceptance testing (instead of keeping 2 days you keep 5 days for acceptance testing)
or a senior architect review – you know that the review would take only 4 hours but he is a senior resource and might be travelling and other activities are dependent on it so you keep 5 days for senior architect review.  It might happen that the senior guy may not do the review even after 5 days because you followed up only on 5th day about the review status..
Instead, if you would have given him 4 hours (by asking his availability) and to handle any delays would have kept 4 days as “Feeding buffer” you would have gained 3 things:
  1. Optimal follow up on the activities 
  2. Absorption of delay – meeting the deadline to start the next activity ( because you kept 4 days as buffer)
  3. Better estimation for your project and forcing projects for your organisation
So next time when you plan your project, implement critical chain as the best practice!!