Two User Interaction Design Processes

Agile UI Design Process:

Evolving since the mid-1990s, the Agile design process performs many of the same tasks as 'waterfall', but replaces waterfall's lengthy documents with models and visual descriptions, and admits users into the project team. Preferred for incremental releases of live code.

This article illustrates the various artifacts (e.g., card sorting approach to task analysis) developed by an agile team.

Waterfall UI Design Process:

In use since the mid-1970s, the waterfall design process comprises sequential design steps, which complete phases in one discipline before passing them to another phase using a different discipline (e.g., design => coding).

This article lists and discusses the artifacts (e.g., functional specification, wireframes, etc.) the interaction designer develops.

How these Methods Compare:

The Agile Manifesto states that Agile development prefers:

Individuals and interactions more than processes and tools
Models and working software more than documentation
User and customer collaboration more than contract negotiation
Responding to change more than following a plan