Builder Pattern:
The Builder Pattern is a creational design that provides a flexible solution for constructing complex objects step by step. This pattern is typically used for constructing objects that require many steps to create, some of which may be optional. It separates the construction of an object from its representation, so the same construction process can create different representations. This pattern is useful when you want to hide the details of object creation and encapsulate the process in its own class (the builder class).

Pros of the builder pattern:
1. Control over what steps to run and when.

2. Isolate complex construction code from the business logic of the object (Single Responsibility Principal).

3. Flexibility to create different representations using the same object construction process.

Suppose to want to make a pizza. In this scenario, the pizza is the complex object we want to construct. Each pizza can have different combinations of toppings.

Implementation in Go:


Another example:


To sum up, the builder pattern is a flexible pattern that separates the object construction process from the object itself allowing creation of a variety of object types. Think of the pizza builder, capable of crafting many pizza types from the same set of steps.