What are Design Patterns and why you should know them?

1. What are design patterns?

After you have implemented a specific functionality in your project, did you ever have to refactor so many things in order to only add one functionality?
Have you ever worked on a team and spent a huge time only merging the code together and less time in feature development?
After you finish your project and after 2 to 3 weeks, your project manager asks you to add functionality and you spend lots of hours only to understand the code you have previously written.
Do you feel your code is coupled too much with each other and a small change in one class might end up refactoring all the other classes which do not even implement or use those methods?
Did you refactor the code of your teammate in order to understand it first?

Patterns allow you to say more with less. When you use a pattern in a description, other developers quickly know precisely the design you have in mind.
You will have more robust and loosely coupled code, therefore if you want to add more functionality to it then you can pretty much add those without dealing with old code and refactoring those again and again.
Your code will become more testable and maintainable because all your classes and abstractions will be having unique roles and responsibilities.
After you learn those patterns, it will be like this:

Creational design pattern: It deals with how objects are created. They provide various object creation mechanisms, which relate to flexibility and reuse of code.
Structural design pattern: It deals with how objects relate to each other. These patterns explain how to group objects and classes into larger structures while keeping these structures flexible and efficient.
Behavioral design pattern: It deals with how objects communicate with each other. These patterns are concerned with algorithms and the assignment of responsibilities between objects.

I am gonna start to cover all these patterns in my upcoming articles. I am gonna write and implement these patterns in dart but these patterns can be applied to basically any language.