“So, what is PHP? Right now its developers call it an open
source server-side HTML-embedded scripting language, but PHP seems
destined to evolve beyond its HTML roots into more advanced
services like remote procedure calls (for example, there’s
already an XML-RPC client and server). PHP can be embedded into an
HTML page within XML or even plain text.”
“Like JavaServer Pages (JSP) and Microsoft’s Active Server Pages
(ASP), PHP is, at its heart, a tool for generating dynamic content
on Web pages. All three let you embed commands (e.g. “print the
latest sales numbers from the database”) into an otherwise static
HTML page. Other than the fact that PHP is Open Source, the main
difference between it, JSP, and ASP has to do with syntax. JSP uses
Java as its programming language while ASP allows both VBScript and
JScript (Microsoft’s version of JavaScript). PHP uses its own
programming language, with syntax and features derived mostly from
Perl, Java and C.”
“The most common way to run the PHP engine — without which all
of those embedded PHP commands simply won’t work — is to run it as
an Apache module (PHP has a NASPI version for Netscape servers, as
well as an ISAPI version for Microsoft’s IIS, but neither are
really production-ready). The alternative is to build PHP as a CGI
and configure your Web server to handle .php files with the PHP
executable, much like Perl can be configured to handle files with
the .pl extension. Linux Magazine recommends running PHP as an
Apache module as this method gives you the best performance.”