............ like a recipe, except that the ingredients used to create a
pattern are object-oriented principles.

we use class because a pattern defines a best practice based on an
implementation that has proven itself to be useful when developing
applications

Each pattern describes a problem which occurs over and
over again in our environment.

Of The following Types of pattern design

Behavioral the purpose of this type is to bring together existing
objects

...............includes Façade , Adapter, Bridge and Decorator

Facade and Adapter patterns usually used relating implementation with abstraction

Bridge and Decorator used for relating implementation with abstraction.

............The purpose of this type is to Give a way to manifest
flexible (varying) behavior ,this type is a strategy .It is used for containing
variation.

............includes Abstract Factory, Singleton ,Double-Checked Locking and
Factory Method

Creational:

Provide a unified interface to a set of interfaces in a subsystem

Adapter defines a higher-level interface that makes the subsystem
easier to use

Subsystem classes

..............pattern is a versatile(many ways of use ) pattern that joins together types
that were not designed to work with each other.

In Adapter Pattern alterations to the original code are required.

•The role of the .............. pattern is to provide a way of attaching new
state and behavior to an object dynamically.

There are several kinds of proxies except:

.................supports objects that control the creation of and access to
other objects

The proxy is often a small (public) object that stands in for a more
complex (private) object that is activated once certain circumstances are clear.

..................are concerned with algorithms and
communication between them.