Explain different design patterns

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Design patterns are reusable solutions to common problems in software design.

Design patterns help in creating flexible, maintainable, and scalable software.
Some common design patterns include Singleton, Factory, Observer, and Strategy.
Singleton pattern ensures a class has only one instance and provides a global point of access to it.
Factory pattern creates objects without specifying the exact class of object that will be created.
Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated.
Strategy pattern defines a family of algorithms, encapsulates each algorithm, and makes them interchangeable.

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