Static web pages are often HTML documents stored as files in the file system and made available by the web server over HTTP (nevertheless URLs ending with ".html" are not always static). However, loose interpretations of the term could include web pages stored in a database, and could even include pages formatted using a template and served through an application server, as long as the page served is unchanging and presented essentially as stored. Static web pages are suitable for the contents that never or rarely need to be updated, though modern static site generators are changing. Maintaining large numbers of static pages as files can be impractical without automated tools, such as Static site generators described in Web template system. Any personalization or interactivity has to run client-side, which is restricting.