What is design pattern?
A design pattern is a re-usable solution to common problem which software developers faced during software development.
They are not finished design. They are the summary of practical experience during software development process with object-oriented programming language. They are drawn from numerous developers' previous lessons learned over substantial period of time.
How many design patterns are there?
23. The 23 GoF design patterns are generally considered the foundation for all other patters.
What is GoF?
The abbreviation of Gang of Four. Four authors of the book Design Patterns: Elements of Reusable Object-Oriented Software, which was published in 1994. Words design patterns gained popularity after this book publication.
The four authors are Erick Gamma, Richard Helm, Ralph Johnson and John Vlissides.
