X11
X11, also known as the X Window System, is a network-transparent windowing system for bitmap displays, primarily used on Unix-like operating systems. It provides a framework for building graphical user interfaces (GUIs) by separating the display server (which manages input/output) from client applications, enabling remote display capabilities. X11 serves as the foundation for desktop environments like GNOME and KDE, handling tasks such as window management, rendering, and event handling.
Developers should learn X11 when working on Linux or Unix-based systems that require GUI development, system-level graphics programming, or remote desktop applications. It is essential for building or customizing desktop environments, writing low-level display drivers, or creating applications that need precise control over windowing and input events, such as scientific visualization tools or embedded systems with graphical interfaces.