How to create a GUI application in Python using Tkinter?

To create a GUI application in Python using Tkinter, follow this detailed step-by-step guide:

Step 1: Import Tkinter

Tkinter is a standard Python library and is included with Python. To use it, we need to import the module in our Python script. 

\`\`\`python
import tkinter as tk
\`\`\`

Step 2: Create a Main Window

Once the Tkinter module is imported, create a main application window.

\`\`\`python
main\_window = tk.Tk()
\`\`\`

Step 3: Add Widgets

The next step is to add some widgets (buttons, labels, text boxes etc.) in the application. Let's say we want to add a label and a button in our application.

\`\`\`python
greeting = tk.Label(text="Hello, Tkinter")
greeting.pack()

close_button = tk.Button(main_window, text="Close", command=main\_window.quit)
close\_button.pack()
\`\`\`

In this example, `text` is an option that allows to set the text shown in the label. `command=main_window.quit` is an option of the `Button` widget. It sets the function or method that will be called when the button is pressed.

Step 4: Run the Application Loop

Once all the widgets are created and ready, we can run the application's mainloop.

\`\`\`python
main\_window.mainloop()
\`\`\`

This method will loop forever, waiting for events from the user, until the user closes the window or triggers the `Close` button. 

Here's all the code in one piece:

import tkinter as tk

main_window = tk.Tk()

greeting = tk.Label(text="Hello, Tkinter")
greeting.pack()

close_button = tk.Button(main_window, text="Close", command=main_window.quit)
close_button.pack()

main_window.mainloop()

In this script, we have used the pack() method which is used to organize widgets in blocks one after another. However, the Tkinter library provides other geometry managers that can be used according to your needs, such as grid() and place().

This application will create a simple window with a greeting and a close button. When the close button is clicked, the application will be closed.

Hopefully, this gives you a good starting point to building GUI applications with Python using Tkinter. You can now extend this application with more widgets, stylings, and functionalities based on your needs.