The main components of a Graphical User Interface (GUI) are:

1. Windows: Rectangular areas on the screen that contain other GUI elements.

2. Menus: Lists of options or commands that can be selected by the user.

3. Icons: Small graphics that represent files, programs, or actions.

4. Buttons: Clickable areas that perform actions when clicked.

5. Text Fields: Areas where users can input text.

6. Checkboxes: Small boxes that can be checked or unchecked to select options.

7. Radio Buttons: Small circles that can be selected to choose an option.

8. Sliders: Bars that can be dragged to adjust values.

9. Dialog Boxes: Pop-up windows that provide information or request input.

10. Toolbars: Rows of buttons or icons that provide quick access to common actions.

11. Graphics: Visual elements like images, charts, and graphs.

12. Cursor: A visual indicator of the user's position on the screen.

These components work together to create a user-friendly and intuitive interface for interacting with software applications.