The process of software development involves creating new classes and interfaces, building an inheritance hierarchy, and establishing communication between objects. Object-oriented programming helps us to build an abstraction of entities and processes using extremely powerful concepts such as encapsulations, composition, inheritance, polymorphism, and so on and so forth. 

We should understand that a developer writes code to solve one or more sets of problems. Software designing is a process of describing how to apply the concepts of object-oriented programming together to implement a solution.

An implementation of a commonly occurring solution is a software design pattern if it can be reused in many different situations. The most common reasons to use a design template are as follows:

• Acceleration of the development process
• Increasing the quality of code
• Decreasing communication time between developers

Reusing patterns helps us to prevent common issues, which is why we can increase the quality of code. It also improves readability and understanding for developers who are familiar with a pattern that decreases the time for communication and code review. As a result, we can speed up the development process.

Software design patterns in object-oriented programming show relationships and communications between classes and objects. That's why using a Unified Modeling Language (UML) is a common practice for describing a structure and how to apply a template to your software design. The following diagram represents the Strategy pattern:

This diagram shows a relationships between classes and interface according to the Strategy pattern. We will go over this template further, but first let's look at types of patterns.