• The "plugin" directory is for plugins that should always be loaded whenever Vim starts. These define global commands, interface tweaks, or new functionality useful for all or many file types.
  • The "ftplugin" directory is for filetype-specific plugins, such as autocompletion or highlight-errors-as-you-edit plugins.
  • The "syntax" directory is for updated syntax highlighting rules specific to a file type.
  • The "indent" directory is for filetype-specific indentation rules.
  • The "ftdetect" directory is for filetype-detection rules. Files that go here should usually do nothing but set the filetype so that files in the ftplugin, indent, or syntax directories are loaded for a new filetype.
  • The "colors" directory is for color scheme files.
  • The "doc" directory is for any help file documentation.
  • The "after" directory contains another tree with directories like "plugin", "ftplugin", and "syntax" that can be used to override settings in the system-wide settings or other plugins placed in the normal version of these directories. These files will always be loaded after their counterparts in other directories.

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All about the VIM Folder structure