Vim's interface is not based on menus or icons but on commands given in a text user interface; its GUI mode, gVim, adds menus and toolbars for commonly used commands but the full functionality is still expressed through its command line mode.
Vim has a built-in tutorial for beginners (accessible through the "vimtutor" command). There is also the Vim Users' Manual that details Vim's features. This manual can be read from within Vim, or found online.
Part of Vim's power is that it can be extensively customized. The basic interface can be controlled by the many options available, and the user can define personalized key mappings—often called macros—or abbreviations to automate sequences of keystrokes, or even call internal or user-defined functions.
There are many plugins available that will extend or add new functionality to Vim. These complex scripts are usually written in Vim's internal scripting language, vimscript. Vim also supports scripting using Lua, Perl, Python, Racket (formerly PLT Scheme), Ruby, and Tcl.
Some of Vim's enhancements include completion, comparison and merging of files (known as vimdiff), a comprehensive integrated help system, extended regular expressions, scripting languages (both native and through alternative scripting interpreters such as Perl, Python, Ruby, Tcl, etc.) including support for plugins, a graphical user interface (known as gvim), limited integrated development environment-like features, mouse interaction (both with and without the GUI), folding, editing of compressed or archived files in gzip, bzip2, zip, and tar format and files over network protocols such as SSH, FTP, and HTTP, session state preservation, spell checking, split (horizontal and vertical) and tabbed windows, Unicode and other multi-language support, syntax highlighting, trans-session command, search and cursor position histories, multiple level and branching undo/redo history which can persist across editing sessions, and visual mode.
Vim script (also called vimscript or VimL) is the scripting language built into Vim. Based on the ex editor language of the original vi editor, early versions of Vim added commands for control flow and function definitions. Since version 7, Vim script also supports more advanced data types such as lists and dictionaries and (a simple form of) object-oriented programming. Built-in functions such as map() and filter() allow a basic form of functional programming, and Vim script has lambda since version 8.0. Vim script is mostly written in an imperative programming style.
Vim macros can contain a sequence of normal-mode commands, but can also invoke ex commands or functions written in Vim script for more complex tasks. Almost all extensions (called plugins or more commonly scripts) of the core Vim functionality are written in Vim script, but plugins can also utilize other interpreted languages like Perl, Python, Lua, or Ruby (if support for them is compiled into the Vim binary).
Vim script files are stored in plain text format and the file name extension is .vim. There are libraries for Vim script available on vim.org/ as Vim plugins