Could someone please tell me why a page would need an ASP extension and what ASP pages do?
ASP is used to embed programming and server side directives into a html web page. An ASP aware server will then execute those directives or code as it sends the page out to the internet.
ASP is a Windows only method, though there is the Mono project which will allow ASP.net type stuff on non-windows platforms.
ASP pages are a completely different technology to HTML pages.
ASP is a server-side programming language, which means that the code you write gets sent to a server (or a program) and it returns some code depending on what you told it to do.
I would recommend learning PHP rather than ASP, as it is much more popular, and it’s easier to code, cheaper to host (on a server), and it has much more support.
PHP is similar to ASP, but it’s much more efficient. It’s best pointers are database connections. These can create login systems, product displays and interactive pages. It also helps to make Content Management Systems.
When a web page has an extension such as ASP, PHP, JSP, CFM etc it means that there is a programming language running on the server that dynamically generates the HTML. They all display HTML in the web browser but they use a program to generate it rather than it being statically coded.
They have many advantages. Not only can they help to give websites login systems etc, but they are extremely secure (common sense needed for things like file downloads). No-one apart from you have access the program code.