Emacs

Emacs is a family of versatile and extensible text editors. The ideology of Emacs is based on the principles of all-in-one, extensibility, customizability, and documentability.

Emacs functionality can be divided into three levels: basic, basic mode, and advanced modes. The combination of these three levels allows you to perform a huge number of tasks (including those not directly related to text editing) without leaving the editor.

Basic functionality includes basic text operations, both present in any editor, and unique to Emacs. These include inserting and deleting text, moving through text, opening and saving files, etc. Unique to Emacs is the multitude of these operations and the accessibility of almost all of them from the keyboard. For example, you can move through text character by character, words, lines, pages, sentences, paragraphs, balanced lists (that is, expressions enclosed in brackets), and functions.

The basic Emacs mode is determined by the type of file being edited. There are modes for different programming languages, for text markup languages (HTML, TeX, etc.), for browsing directories, for reading and sending emails, and many others. Basic mode defines the way syntax is highlighted, the way code is aligned for programming languages, special commands for commonly used operations, etc. Basic mode can also override basic text elements. For example, when editing programs in C and similar languages, a sentence is considered a single program instruction. In this case, in the comments, the sentence has the usual textual meaning.

Additional modes usually provide functionality that is independent or weakly dependent on the format of the file being edited. Unlike the main mode, which for any buffer is one, the number of active additional modes is not limited. For example, there are modes for highlighting the current line, permanent output of current function name for program texts, highlighting of matching brackets and many others.