What is a design pattern?

Purpose:

• Familiarity with design patterns are a great indication that someone has a good theoretical understanding of the software industry.
• It is usually a good indicator for passion and whether a developer cares about formalizing and mastering their craft.
• Design pattern ignorance may show a general lack of interest in mastering their craft and suggest perhaps a code-by-google fashioned recipe coder that lacks an in depth reasoning of their designs.

Potential Answer:
As software development matured as an engineering field it was identified that like other engineering fields there are recurring problems and solutions that present themselves. So like other engineering fields software practitioners started formalizing so called design patterns. A design pattern provides low level solution (implementation) for the commonly occurring object oriented problem.

That is design patterns suggest a specific implementation for the specific object oriented programming problem. For example, if you want create a class that can only have one object at a time then you can use Singleton design pattern which suggests the best way to create a class that can only have one object.

What would be good to talk about is the fact that design patterns provide software practitioners with a common vocabulary to talk about software construction and design.