In software development, a  design Pattern describes a general solution to a design problem that recurs repeatedly in many projects. Software designers adapt the Pattern solution to their specific project. Patterns use a formal approach to describing a design problem, its proposed solution, and any other factors that might affect the problem or the solution. A successful Pattern should have established itself as leading to a good solution in three previous projects or situations.

Here are 3 categories of the Patterns involved in software designing...
1) Creational Patterns

• Abstract factory pattern: centralize decision of what factory to instantiate
• Factory method pattern: centralize creation of an object of a specific type choosing one of several implementations
• Anonymous subroutine objects pattern
• Builder pattern: separate the construction of a complex object from its representation
• Lazy initialization pattern: tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the needed first time
• Prototype pattern: used when the inherent cost of creating a new object in the standard way (e.g., using the 'new' keyword) is prohibitively expensive 
• Singleton pattern: restrict instantiation of a class to one object
  2) Structural Patterns
• Adapter pattern: 'adapts' one interface for a class into one that a client expects
• Composite pattern: a tree structure of objects where every object has the same interface
• Aggregate pattern: a version of the Composite pattern with methods for aggregation of children
• Bridge pattern: decouple an abstraction from its implementation so that the two can vary independently
• Container pattern: create objects for the sole purpose of holding other objects and managing them
• Decorator pattern: add additional functionality to a class at run time where subclassing would result in an exponential rise of new classes
• Extensibility pattern: aka. Framework - hide complex code behind a simple interface
• Facade pattern: create a simplified interface of an existing interface to ease usage for common tasks
• Flyweight pattern: a high quantity of objects share a common properties object to save space
• Proxy pattern: a class functioning as an interface to another thing
• Pipes and filters: a chain of processes where the output of each process is the input of the next
• Private class data pattern: restrict accessor/mutator access
  3) Behavioral Patterns
• Chain of responsibility pattern: Command objects are handled or passed on to other objects by logic-containing processing objects
• Command pattern: Command objects encapsulate an action and its parameters
• Interpreter pattern:  Implement a specialized computer language to rapidly solve a specific set of problems
• Iterator pattern: Iterators are used to access the elements of an aggregate object sequentially without exposing its underlying representation
• Mediator pattern: Provides a unified interface to a set of interfaces in a subsystem
• Memento pattern: Provides the ability to restore an object to its previous state (rollback)
• Observer pattern: aka Publish/Subscribe or Event Listener. Objects register to observe an event which may be raised by another object
• State pattern: A clean way for an object to partially change its type at run time
• Strategy pattern: Algorithms can be selected on the fly
• Template method pattern: Describes the program skeleton of a program
• Visitor pattern: A way to separate an algorithm from an object
• Single-serving visitor pattern: Optimise the implementation of a visitor that is allocated, used only once, and then deleted
• Hierarchical visitor pattern: Provide a way to visit every node in a hierarchical data structure such as a tree

  Look for subsequent posts for clarification of each one from C# point of view...

  Cheers!!!