saving state information in cgi scripts one of the most unusual aspects of the basic cgi modeland one of its starkest contrasts to the gui programming techniques we studied in the prior part of this bookis that cgi scripts are stateless--each is standalone programnormally run autonomouslywith no knowledge of any other scripts that may run before or after there is no notion of things such as global variables or objects that outlive single step of interaction and retain context each script begins from scratchwith no memory of where the prior left off this makes web servers simple and robust-- buggy cgi script won' interfere with the server process in facta flaw in cgi script generally affects only the single page it implementsnot the entire web-based application but this is very different model from callback-handler functions in single process guiand it requires extra work to remember things longer than single script' execution lack of state retention hasn' mattered in our simple examples so farbut larger systems are usually composed of multiple user interaction steps and many scriptsand they need way to keep track of information gathered along the way as suggested in the server-side scripting