Shared Hosting and Dedicated Hosting
the primary difference between dedicated and shared hosting is how the web server is used. with Shared web hosting, the web server is shared between many different websites. with Dedicated web hosting, the web server is dedicated to your web site. both have their advantages and disadvantages. dedicated hosting is of course much more expensive than shared hosting as you actually use the whole server.

Common Gateway Interface (CGI)
Common Gateway Interface, or CGI, is a standard that allows a web server to execute an external program and send its output to the browser that requested it.

CGI was the original method of creating dynamic web applications. you can write a program in C/C++, Perl, or whatever language can run on your web server computer, and tell the web server to treat it as a CGI program.

Perl is the most popular language used to write CGI scripts.

Server-Side Scripting Languages
server-side scripting languages, such as PHP, ASP, are all intended to fulfill the same role as CGI without the burden of launching an external program for every request.

By installing a plug-in, the web server software knows how to do things like running programs written in Perl or PHP all by itself, instead of having to ask the operating system to run them as separate programs. when a web page containing one of these languages is requested, the web server uses its internal plug-ins to run the code in the page, then send the results to the Web browser.

Perl
Perl is a programming language that excels at manipulation of text. as such, it is ideal for the development of dynamic web pages. this isn’t to say that web development is the only application of Perl – it is heavily used in automation of administrative tasks on Unix-based systems, for example.

PHP
Personal Home Page (PHP) is a somewhat less flexible language than Perl, but is more specialized towards the creation of dynamic web pages. this focus means that you can do pretty much anything you can do with Perl using PHP.

designed for use as a server-side scripting language (whereas Perl was not originally designed for use on the web), this language bears similarities to other common languages (Perl, C/C++, Java, JavaScript) to make it easy for existing programmers to use.

ASP (Active Server Pages)
Active Server Pages (ASP) is a framework for running scripting languages as server-side scripting languages. developed by Microsoft, this is mainly supported by Windows web server. as a solution for creating dynamic web sites, ASP basically fills the same role as PHP, but with some degree of freedom in your choice of programming language. the trade-off is a loss of freedom in your choice of web server software.