GNU Emacs
GNU Emacs is a highly extensible, customizable text editor and integrated development environment (IDE) that runs on various operating systems, including Unix, Linux, macOS, and Windows. It is known for its powerful Lisp-based extension language (Emacs Lisp) and a vast ecosystem of packages for tasks like coding, email, file management, and more. Emacs emphasizes keyboard-driven efficiency and can be tailored to suit almost any workflow through its configuration and scripting capabilities.
Developers should learn GNU Emacs when they need a highly flexible and programmable editor for complex text manipulation, coding in multiple languages, or integrating diverse tools into a single environment. It is particularly valuable for tasks requiring automation, such as batch editing, or for users who prefer a keyboard-centric workflow to boost productivity in software development, system administration, or academic writing.