Before addressing the specifics of Business Analysis for Information Systems, I would like to define (or attempt to define) just what an Information system is.
Computers are used for many different purposes, often with very specialized hardware and software; examples range from missile guidance systems, to supercomputers crunching numbers for scientists at high speeds. On the other hand, personal computers and the internet that use common hardware and software platforms have become a part of daily personal life, whether to play more and more sophisticated video games, or to write blogs, among other things.
However, if you use a computer as a regular part of your workday, you are likely not doing any of the things mentioned in the previous paragraph. Instead, you are probably using a computer to do business as part of your job in the private or public sectors; you might also be self-employed or otherwise own your own business, but in any case, I know you are not playing Half-Life 2... you are most definitely using an "Information System".
When considering the basic principles that support what I do as a Business Analyst, I refer back a few decades to Finklestein and Martin's statement that "Information = Data and Process"; you can supplement that with the common axiom that "information is power". All this has been true since the origins of the abacus, through to the punch cards first used for collecting census data over 100 years ago, to the arrival of digital computers in the 20th century.
Today, we now have computers and networks and publishing media and related technologies that can be used to effectively gather and use information in support of "business" activities. (In this context, "business" encompasses public and private enterprise, profit and non-profit organizations, i.e. virtually any grouping of activities that use information to reach the desired goal of those activities.)
And that is all I am going to say about "what is an Information System...", at least for now. I have stayed away from creating a dictionary-style definition, mainly because I have never liked the ones I have read in dictionaries in the past. However, if you have a succint definition that captures what I have said in this post, please send it along and I will share it and all I receive in a future post... then we should send them to Websters , and Funk & Wagnell(!).
Next time: what is it we can "require" an Information System to do...
Cheers, Dave W