Server Side Includes

Server Side Includes (SSI), or Server-parsed HTML (SHTML), is a simple scripting language used to create dynamic web pages. Like PHP, SSI directives are typically embedded in a file that is otherwise in HTML format. The web server parses the file, executes the SSI code, and replaces the code with the code's output.

Today's templating engines have more or less rendered SSI obsolete.

Discussion
Definitive information about the origin of SSI is hard to come by, but we believe it was created by Rob McCool in 1993–1994, as part of the NCSA HTTPd web server software. A primitive version of it appeared in NCSA HTTPd 1.1 (1994-01). In that version, directives begin with the string: &lt;inc srv

NCSA HTTPd 1.2 (1994-04) introduced the modern syntax, in which directives masquerade as HTML comments, and begin with: &lt;!--#

NCSA HTTPd 1.2+ included a tool, inc2shtml.c, to convert from the old to the new syntax.

Variants
[TODO: There are a number of variants of SSI, including something called XSSI (eXtended Server Side Includes).]

Software

 * NCSA HTTPd (historical)
 * A handful of modern web servers support SSI as an option. For example:
 * Apache HTTP Server → mod_include
 * nginx → ngx_http_ssi_module

Links

 * Server Side Includes
 * NCSA HTTPd
 * Documentation for Apache mod_include