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6 essential software design principles programmers must know

Updated: May 7

Software design patterns

Software design principles are fundamental guidelines and best practices used in the planning and development of software systems. These principles help manage the inherent complexity of software design by making the process more effective and reducing the likelihood of errors. In the long term, following these principles supports functionality and ease of modification.

What is software design?

Software design involves specifying the architecture, components, interfaces, and data for a system to satisfy specified requirements. This process includes defining methods, functions, objects, and the overall interaction within your code. By following software design steps, the final product meets user needs effectively.

Importance of software design in software engineering 

A well-thought-out design enhances a software’s clarity, adaptability, reliability, and reusability. It acts as a bridge connecting the challenges posed by the user’s needs to the practical solutions that the software will offer. You can write code without following software design principles, but mastering these principles and knowing what design patterns are is essential for advancing to senior-level positions. Design patterns provide tried and tested solutions to recurring problems in software development, enhancing maintainability and reducing risks. Observing how frameworks like Laravel and Spring implement these principles, such as through the Dependency Inversion Principle, can significantly sharpen your software development skills.

Here are the benefits of applying design principles in software engineering:

  • Encourages modularity in software engineering: Facilitates the use of the same code in different parts of the software, making the system more modular.

  • Promotes loose coupling: Reduces dependencies between components, which simplifies changes and enhancements. This also introduces an element of abstraction in software engineering because when components are designed to interact with each other through simple, abstract interfaces rather than direct implementations, it reduces dependencies and simplifies interactions.

  • Enhances readability and maintainability in software engineering: Makes the code easier to understand and modify, which helps in maintaining the software efficiently.

  • Improves testability and scalability: Assists in creating systems that are easier to test and scale up as needed.

  • Facilitates collaboration: Helps team members work together more effectively by using a common set of design practices.

What are the main principles of software design?

1. solid

Solid software design principles are a set of five principles that provide guidelines in object-oriented programming: 

  • Single Responsibility Principle (SRP): A class should have only one reason to change, focusing on a single task to enhance maintainability and reduce complexity.

  • Open/Closed Principle (OCP): Software entities should be open for extension but closed for modification, allowing new functionalities to be added without altering existing code.

  • Liskov Substitution Principle (LSP): Objects of a superclass should be replaceable with objects of its subclasses without affecting the application, ensuring that derived classes adhere to their base class’s behavior.

  • Interface Segregation Principle (ISP): Larger interfaces should be divided into smaller, more specific ones to prevent classes from depending on interfaces they do not use, enhancing code modularity and clarity.

  • Dependency Inversion Principle (DIP): High-level modules should not depend on low-level modules but on abstractions, fostering a loosely coupled architecture that simplifies maintenance and increases flexibility.

2. DRY

The DRY (Don't Repeat Yourself) principle is a key software development guideline that discourages code duplication, advocating for a single representation of every piece of knowledge in a system. It promotes code reuse through techniques like functions, inheritance, modularization, and design patterns. By minimizing redundancy, the DRY principle streamlines bug fixes and feature development so that changes need to be made in only one place, thereby reducing errors and inconsistencies.


The KISS (Keep It Simple, Stupid) principle encourages keeping solutions as straightforward as possible. It recommends simplicity in code architecture, algorithm choices, and during refactoring. By applying KISS, developers can write code that is easier to read, debug, and extend, ensuring a smoother workflow and better project outcomes.


The YAGNI (You Aren't Gonna Need It) principle advises software developers to implement features only when they are truly necessary. So, you should avoid the temptation to build functionalities based on anticipated future needs. Focusing on the current requirements reduces complexity and minimizes resource waste. It is particularly effective in Agile environments, promoting iterative development and helping teams prioritize essential features while maintaining the flexibility to adapt as project needs evolve.

5. Composition over inheritance

Using composition—combining simple objects to build complex ones—rather than inheritance leads to greater flexibility and reduces code complexity. So your code is more maintainable with smaller, task-specific components that enable runtime changes, unlike the static nature of inheritance. It's particularly useful when functionalities need to be mixed without a clear hierarchical relationship.

6. Law of Demeter

The Law of Demeter, also known as the Principle of Least Knowledge, reduces the coupling between software components by restricting how much one object knows about another. So interactions are only with immediate neighbors, minimizing direct property accesses through method delegation. Developers can avoid over-complication by creating a more maintainable, scalable, and bug-resistant codebase.

Start learning principles of design patterns

Now that you’re familiar with the key software design principles, consider learning with design patterns. Enroll in the “Software Design Patterns: Best Practices for Software Developers” course to advance your career. This course will guide you through applying established patterns, helping you write code that is extensible, maintainable, and flexible. It’s an excellent way to demonstrate the superior skills expected of a seasoned software engineer.

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