The first version of this book was not a planned activity, it just happened. Somewhere in 2007 or 2008, on some mailing list I happened to see a post from a mathematics teacher, Dr C V Ramesan, Calicut, asking for suggestions to include some IT stuff in the BSc syllabus. Free Software only was considered and Octave, R, Scilab etc. were under consideration. I casually suggested Python because it has modules like numpy, scipy and matplotlib that can do scientific computation. Also Python skills may help the student later in the job market. The communication continued and a syllabus was prepared. Initially ther was not textbook but later, our request, Pramode C E wrote a book. In 2010 someone else published a book that explains howto use Python on MSWindows only, no mention about GNU/Linux platforms. Dr Ramesan wanted a book that highlights Free Software aspect, as quickly as possible. I had some notes, used during the ExpEYES training sessions, and the so called book was prepared within a couple of weeks. The Lyx skills learned from Pramode turned out to be of greate help in preparing it. Printed version is made available by Calicut University Press.