Reflow is the name of the web browser process for re-calculating the positions and geometries of elements in the document, for the purpose of re-rendering part or all of the document. Because reflow is a user-blocking operation in the browser, it is useful for developers to understand how to improve reflow time and also to understand the effects of various document properties (DOM depth, CSS rule efficiency, different types of style changes) on reflow time. Sometimes reflowing a single element in the document may require reflowing its parent elements and also any elements which follow it.
Behavior Driven Development.
In software engineering, behavior-driven development (abbreviated BDD) is a software development process based on test-driven development (TDD). Behavior-driven development combines the general techniques and principles of TDD with ideas from domain-driven design and object-oriented analysis and design to provide software developers and business analysts with shared tools and a shared process to collaborate on software development, with the aim of delivering “software that matters”.