During the pioneer area of the World Wide Web, the content was static. To serve it, a group of developers created a web server, which is now known as the Apache Web Server.
The Apache Web Server is built around a module architecture. Developers created a module to run CGI scripts to add dynamic content to the lot. Users wrote early CGI scripts in Perl. After a while, it became evident that generating a complete HTML page from scratch was not the best way and that templating - providing an HTML page with placeholders - was a much better approach. The PHP language started like this as a simple templating engine interpreted by a module.