The Free On-line Dictionary of Computing (30 December 2018):

server-side

    Processing or content generation that is done
   on the web server or other server, as opposed to on the
   client computer where the web browser is running.

   An example is server-side include where one file is inserted
   in another before it is served, rather than, say, having the
   browser request the files separately and combine them using an
   iframe.  A very common kind of server-side processing is the
   inclusion of data from a database in a web page.

   There are many software environments and technologies designed
   for server-side processing, e.g. CGI, ISAPI, WebObjects
   and ASP.

   The greatest advantage of server-side processing is that it is
   independent of the many different client software environments
   that exist on the Internet, chiefly different web browsers
   and operating systems.  The disadvantage is that the user
   must wait for a response from the server which is a much
   slower form of interaction than is possible with client-side
   processing using, e.g., JavaScript.

   (2003-12-29)