FeatureBranch v/s FeatureToggle v/s BranchByAbstraction patterns

This blog is excerpts from Martin Fowler blog and Continuous Delivery book (Jez Humble, David Farley). It explains about the concepts of
1) Feature Branch
    http://martinfowler.com/bliki/FeatureBranch.html
2) Feature Toggle
    http://martinfowler.com/bliki/FeatureToggle.html
3) Branch By Abstraction
    http://continuousdelivery.com/2011/05/make-large-scale-changes-incrementally-with-branch-by-abstraction/

    This post explains how to avoid branching in Source control.