GNU Readline is a library for command line editing. The most prominent program that uses it is Bash bash, and bash and readline have the same maintainer. Many other programs with a command line interface use it, for example the Python python toplevel. Readline's capabilities include basic editing facilities, command history, (internal) copy-paste and completion.
The configuration file for readline is
The rlwrap utility provides readline's capabilities to programs that just read from standard input.