The Termcap package contains the termcap library.
The termcap library contains C functions that enable programs to send control strings to terminals in a way independent of the terminal type. The GNU termcap library does not place an arbitrary limit on the size of termcap entries, unlike most other termcap libraries.
The use of termcap is discouraged. Termcap is being phased out in favor of the terminfo-based ncurses library, which contains an emulation of the termcap library routines in addition to an excellent curses implementation. The reason for having Termcap installed is there are one or two programs that specifically need this library and don't know about the NCurses library (yet).