persistent processessession managementand so on we'll explore most of these in later examplesbut since this is core idea in server-side scriptinglet' take brief look at each of these in turn url query parameters we met these earlier in this hardcoded url parameters in dynamically generated hyperlinks embedded in input pages produced as replies by including both processing script name and input to itsuch links direct the operation of the next page when selected the parameters are transmitted from client to server automaticallyas part of get-style request coding query parameters is straightforward--print the correctly formatted url to standard output from your cgi script as part of the reply page (albeit following some escaping conventions we'll meet later in this here' an example drawn from the next webmail case studyscript "onviewlistlink pyuser 'bobmnum pswd 'xxxsite pop myisp netprint('view % (scriptuserpswdmnumsitemnum)the resulting url will have enough information to direct the next script when clickedview query parameters serve as memoryand they pass information between pages as suchthey are useful for retaining state across the pages of single session of interaction since each generated url may have different attached parametersthis scheme can provide context per user-selectable action each link in list of selectable alternativesfor examplemay have different implied action coded as different parameter value moreoverusers can bookmark link with parametersin order to return to specific state in an interaction because their state retention is lost when the page is abandonedthoughthey are not useful for remembering state from session to session moreoverthe data appended as url query parameters is generally visible to users and may appear in server logfilesin some applicationsit may have to be manually encrypted to avoid display or forgery hidden form input fields we met these in the prior section as wellhidden form input fields that are attached to form data and are embedded in reply web pagesbut are not displayed in web pages or their url addresses when the form is submittedall the hidden fields are transmitted server-side scripting