Four Essential Elements to a Design Pattern

1. Pattern Name - the handle used to describe a design problem, its solutions, and consequenes. Allows design at a higher level of abstraction.
2. Problem - describes when to apply the pattern. Describes the problem and its context.
3. Solution - describes the elements that make up a design, their relationships, responsibilities, and collaborations. A template that can be applied in many different situations. Provides an abstract description of a design problem and how a general arrangement of elements (classes and object) solves it.
4. Consequences - the results and trade-offs of applying the pattern. Critical in evaluating design alternatives and understanding the costs and benefits of applying the pattern.