gschem is the schematic capture program/tool which is part of gEDA.
Its sole purpose is to facilitate the graphical input of
components/circuits.

  Schematic capture is a fancy name for the ability to draw and
layout circuits using a computer.  Standard symbols are used to
represent the various gates and components which are interconnected
by nets (wires).  Most vector drawing programs can be used for
schematic capture but they usually lack one (or more) of the
following characteristics:

 * The awareness of the electrical properties of components, nets,
   and pins.
 * Hierarchical design (having components represent some abstracted
   functionality).  The ability to associate attributes with nets and
   components.
 * Generate netlists from the schematic.

  These are all critical features (among others which I cannot recall
right now) which are shared by all schematic capture programs.  The
schematic capture program which is part of gEDA is called "gschem".