How are html, css, xml, mysequal, and php related?

[onthis]

Ok, I read "why tables for layout is stupid", so I returned to my html tutorials and started Css tutorials.
But I am little confused about what version of html I should be using to make external style.css work.

I mean xhtml appears to be the version of html that is suposed to work best CSS external style sheets mode. External style sheets is what i need to learn because my goal is to create more than one website of at least a few pages each.

Now during my html, css webpge bLding referencing, googling while keeping out an eye for hosting, php xml, mysequal are constently being referred to.

Second Question is: what are the role and function how of php, xml, mysequal in the web page building and maintainance process. I need to uderstand how all the pieces fit.
Thanks

 

[RaptorRex]

To use xHTML or HTML is debatable and I won't take sides. You want to write in HTML 4.01 if you choose HTML. Either xHTML or HTML 4.01 is great for using external style sheets. Just be sure you use the DOCTYPE element at the top of all your pages.

php, xml, mysql:

xml is a language for describing data. xHTML is an xml document that describes the content of your web page. CSS tells the browser how to display the content. xml can be used to describe any kind of data once somebody describes how to do it. For example the steel industry has defined something called SteelXML which is used to describe the properties of metals. Organizations that adopt SteelXML can then easily share data with other organizations. (the same way we easily exchange web content via browsers).

php is a scripting language that is generally part of your HTML document. The server presenting your HTML document will read the php portions of the page, interpret the php script then send appropriate information to the browser. For example these message boards are probably written with PHP. When you load a message the php on the HTML doc will access a database and insert HTML onto the page which displays this message.

mySQL is a relational database server supporting Structured Query Language. So if you need to save lots of data you can save it to a mySQL server using SQL statements. The data is stored in table format. Often PHP will create the SQL statements which it then sends to the SQL server. The SQL server sends back the data requested (or saves data, or whatever).

I hope that help. It is rather quick and high level but I hope it gives you the idea.