The xterm program is the standard terminal emulator for the X Window System. It provides DEC VT102/VT220 and Tektronix 4014 compatible terminals for programs that can't use the window system directly. If the underlying operating system supports terminal resizing capabilities (for example, the SIGWINCH signal in systems derived from 4.3bsd), xterm will use the facilities to notify programs running in the window whenever it is resized.
Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells. Each virtual terminal provides the functions of the DEC VT100 terminal and, in addition, several control functions from the ANSI X3.64 (ISO 6429) and ISO 2022 standards (e.g., insert/delete line and support for multiple character sets).
rlwrap is a readline wrapper, a small utility that uses the GNU readline library to allow the editing of keyboard input for any other command. It maintains a separate input history for each command, and can TAB-expand words using all previously seen words and/or a user-specified file.
x11vnc allows one to remotely view and interact with real X displays (i.e. a display corresponding to a physical monitor, keyboard, and mouse) with any VNC viewer. It is designed to be compatible with all Unix variants and Mac OS X, and depends on a small set of standard libraries. It supports SSL/TLS and VeNCrypt encryption, Unix password logins, single port access, Zeroconf, file transfer, and UltraVNC extensions. It is part of the LibVNCServer project.
Conserver provides remote access to serial port consoles and logs all data to a central host. Local and network serial connections are supported. Server console history can be replayed from the console app even if the server is down, and multiple users can connect to a single serial connection.
vlock is a program to lock one or more sessions on the Linux console. This is especially useful for Linux machines which have multiple users with access to the console. One user may lock his or her session(s) while still allowing other users to use the system on other virtual consoles. If desired, the entire console may be locked and virtual console switching disabled.
dvtm brings the concept of tiling window management, popularized by X11-window managers like dwm, to the console. As a console window manager, it tries to make it easy to work with multiple console based programs like vim, mutt, cmus, or irssi. dvtm is intended to be used where X11 isn't available or over SSH. In conjunction with dtach, it can be seen as a lightweight alternative to GNU screen.
Twin is a text-mode window environment. It turns a text terminal into a X11-style display with window manager, terminal windows, and can also serve as display for remote applications. Each terminal window provides the functions of a text-mode Linux console. Twin runs on X11, libggi, itself, the Linux console, and any termcap/ncurses-compatible tty. It supports multiple simultaneous displays, and can attach/detach each display on the fly.
Eterm is a vt102 terminal emulator intended as a replacement for xterm. It is designed with a Freedom of Choice philosophy, leaving as much power, flexibility, and freedom as possible in the hands of the user. It is designed to look good and work well, but takes a feature-rich approach rather than one of minimalism. Current features include color support, background images (all Imlib-supported formats), theme support, and pseudo-transparency.