Emacs
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 editing capabilities, built-in support for numerous programming languages, and a vast ecosystem of packages and modes that extend its functionality beyond basic text editing. Emacs operates primarily through keyboard commands and a Lisp-based scripting language (Emacs Lisp), allowing users to tailor it to their specific workflows.
Developers should learn Emacs when they need a highly customizable and programmable editor for tasks such as software development, system administration, or writing documentation, especially in environments where efficiency and automation are priorities. It is particularly useful for working with multiple programming languages, managing large codebases, or integrating with tools like version control systems and debuggers, as its extensibility allows for seamless workflow integration and productivity enhancements.