document formatting programs and programs that you rate yourself and what you can do is to think of these UNIX system programs basically as in some sense the building blocks with which you can create things and thing that distinguishes UNIX system from any other system is the degree to which those building blocks can be glued together in a variety of different ways not just obvious with many cases very on obvious ways to get different jobs done are the system is very flexible in that respect I think the notion pipeline is the fundamental contribution at the system you can take a buncha programs two or more programs and stick them together in the end so that the data simply flows from the one on the left the one on the right and the system itself looks after all the connections