What are Design Patterns?
One of the most relevant books in software engineering was design patterns: Elements of Reusable Object-Oriented Software, 1994, written by theGoF (Gang of Four): Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides. This book presented about two dozen different OOP patternsand has been recognized as a highly important book in computer science.
Note
Patterns are actually a concept from architectural design, originally defined by an architect, Christopher Alexander.
In software terms, a design pattern is a generally applicable, reusable solution, to a usually seen, common problem in software design. Rather than a specific, finished and coded design, it's a description of a solution (the word templateis also used) that can solve a given problem that appears in many contexts. Given their advantages, design patterns are on their own best practices, which can be used by developers working with different kinds of systems, programming languages, and environments...