How to create a GUI in Python?

Creating a GUI (Graphical User Interface) in Python involves using a module like Tkinter, PyQt or wxPython. The following is an example of how one might use the Tkinter module to create a simple window:

```
from tkinter import *

Create instance of TK
root = Tk()

Add a label
label_1 = Label(root, text=‘Hello, World!’)
label_1.pack()

Run the GUI
root.mainloop()
```

Let’s break down the code :

1. `from tkinter import *`

This line imports the whole `tkinter` module into your script.

1. `root = Tk()`

This creates the main window of your application. All components of your application are part of this main window.

1. `label_1 = Label(root, text=‘Hello, World!’)`

This creates a new Label widget. It’s a simple text label that you can place anywhere in your window.

1. `label_1.pack()`

This `pack()` method calculates the size of the window based on the element included in the window.

1. `root.mainloop()`

This line tells Python to run the Tkinter event loop. This method call enters the Tkinter event loop, where the application will stay until the quit function is called.

Remember that creating a complex, full-featured GUI (with buttons, input fields, etc.) can get quite complex, and ideally requires knowledge of object-oriented programming. However, Tkinter is a good module to start with for simple GUI applications.