  Starting from the basic ideas of mathematica, we give a detailed description
about the way of linking of external programs with mathematica through proper
mathlink commands. This article may be quite helpful for the beginners to start
with and write programs in mathematica.
  In the first part, we illustrate how to use a mathemtica notebook and write a
complete program in the notebook. Following with this, we also mention
elaborately about the utility of the local and global variables those are very
essential for writing a program in mathematica. All the commands needed for
doing different mathematical operations can be found with some proper examples
in the mathematica book written by Stephen Wolfram \cite{wolfram}.
  In the rest of this article, we concentrate our study on the most significant
issue which is the process of linking of {\em external programs} with
mathematica, so-called the mathlink operation. By using proper mathlink
commands one can run very tedious jobs efficiently and the operations become
extremely fast.
