SSI, for Server Side Includes, is actually a sort of server-side programming language interpreted by Nginx. Its name is based on the fact that the most used functionality of the language is the include
command. Back in the 1990s, such languages were employed in order to render web pages dynamic, from simple static .html
files with client-side scripts to complex pages with server-processed compositions. Within the HTML source code, webmasters could now insert server-interpreted directives, which would then lead the way to more advanced pre-processors such as PHP or ASP.
The most famous illustration of SSI is the quote of the day. In order to insert a new quote every day at the top of each page of their website, webmasters would have to edit out the HTML source of every page, replacing the former quote manually. With Server Side Includes, a single command suffices to simplify the task:
<html> <head><title>My web page</title></head> <body> <...