Typically, dotfiles are simply configuration files where software programs store their configuration settings in plain, text-based files or directories.
Syntax: Dot File Name Format Purpose .bash_history File History of commands typed at a Bash command prompt. .bash_logout File Script that's run when logging out of a text-mode Bash shell. .bash_profile File Script that's run when starting up a text-mode Bash shell. .bashrc File Script that's run when starting up a text-mode Bash shell. .DCOPServer_* Filename varies with the computer's name; status file for the Desktop Communication Protocol (DCOP), which is used by KDE to help manage interprogram communications. .dmrc File KDE Display Manager (KDM) configuration file; specifies what desktop environment to run when logging in via KDM. .emacs.d Directory Settings for Emacs, a popular text editor. .esd_auth Housekeeping file for the Enlightened Sound Daemon (ESD), which is part of Linux's sound subsystem. .fonts Directory User-installed font files. .fonts.cache-1 File Listing of user-installed fonts in .fonts. .fonts.conf File Xft font configuration file. .gconf Directory Configuration files used by GConf, a centralized configuration tool associated with GNOME. .gconfd Directory Status files used by GConf. .gimp-1.2 or.gimp-2.0 Directory Configuration file, and perhaps temporary storage space, for the GIMP. Precise filename depends on the version of GIMP being used. .gnome, .gnome2, and .gnome2_private Directory Configurations for GNOME applications. .gtkrc File Configuration information for the GIMP Toolkit (GTK+), which is a GUI development tool used by the GIMP, GNOME, and many other programs. .kde Directory Configuration files for KDE applications. .macromedia Directory Configuration files for Macromedia products, such as Flash Player. .mail or .Mail Directory Mail messages; best managed with your mail program. .metacity Directory Configuration files for the Metacity window manager, which is most commonly used by GNOME. .mozilla Directory Configuration files and cache for the Mozilla and Mozilla Firefox Web browsers. .nautilus Directory Configuration files for the Nautilus file browser used by GNOME. .rhn-applet Directory Housekeeping files for Red Hat.s Update Agent program. .rhn-applet.conf File Configuration file for Red Hat.s Update Agent. .signature File Traditional name for a signature file, which is a few (typically 1.4) lines of text appended to mail messages and newsgroup posts. .ssh Directory Files associated with the Secure Shell (SSH) client program. .themes Directory Themes for desktop environments. .wine Directory Configuration and other files related to the WINE Is Not an Emulator (WINE) tool for running Windows programs in Linux. .Xauthority File Automatically generated file that helps manage connections to the X server (Linux.s GUI environment). .Xclients and .Xclients-default File Script that.s sometimes run when logging into a GUI session. (Not all GUI login methods use this script.) .Xdefaults File Settings file that.s used by certain X programs; can be used to set program defaults. .xfce4 Directory Configuration files for the XFce desktop environment. .xinitrc File Script run when starting X from a text-mode login. .xmms Directory Configuration file associated with the X Multimedia System (XMMS).
Granted, this is not a comprehensive list of all available dotfiles, but more so a general overview of associated file types.