Extension methods allow developers to add new methods to existing types (classes, interfaces, structs) without modifying the original source code or creating a new derived type. A quick metaphor Imagine you've bought a new basic bicycle. It's nice, but wouldn't it be cool if you could add a basket without welding or making permanent changes? That's what Extension Methods in C# are like! So, what are Extension Methods? They let you add new methods (or features) to existing classes (like our bicycle) without changing their original code. The Creation process Make a static method (a method that belongs to a class, not an object) inside a static class (a class that can't be instantiated). The first parameter of this method uses the this keyword and mentions the type (or class) you want to add a method to. The Rules It must be defined in a static class. It must be a static method. The first parameter specifies the type you're extending, prefixed with the this ke