A graphical user interface (GUI) is a type of user interface that allows users to interact with electronic devices, such as computers, mobile phones, and gaming consoles, using visual elements such as windows, icons, and buttons. It is designed to make it easier for users to interact with these devices, as opposed to using a command-line interface, which requires users to type commands. The use of a GUI can make it simpler for users to perform tasks, such as launching applications, opening files, and adjusting settings. A well-designed GUI can also make it easier for users to understand how to use an electronic device, as the visual elements and layout provide context and cues for the user.
Here are some useful links that you might find helpful when learning about graphical user interfaces:
Wikipedia: Graphical User Interface - A comprehensive overview of GUI, including its history, design principles, and implementation: https://en.wikipedia.org/wiki/Graphical_user_interface
How to Design a Good API and Why it Matters - A guide to designing user-friendly and intuitive graphical interfaces, from the perspective of API design: https://www.joelonsoftware.com/2000/06/06/how-to-design-a-good-api-and-why-it-matters/
Human Interface Guidelines - Apple's guidelines for designing user-friendly interfaces on its products: https://developer.apple.com/design/human-interface-guidelines/
Google Material Design - Google's guidelines for designing visually appealing and intuitive interfaces, with a focus on material design principles: https://material.io/design/introduction/#principles
GUI Design Handbook - A collection of articles and resources on designing graphical user interfaces, covering topics such as layout, color, typography, and accessibility: http://www.guiddesign.com/
GUI Design Tutorial - A tutorial on designing graphical user interfaces, covering the basics of layout, typography, color, and iconography: https://uxdesign.cc/gui-design-tutorial-e2e1ed3f8c3d