how to edit a php website ?

very Web developer has to know the building blocks of the Web site editing using some html page,css stylesheet and more:
• HTML 4.01
• CSS
• XHTML
• XML and XSLT
• JavaScript
• ASP or PHP
• Managing data with SQL
• The future of the Web
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HTML 4.01
HTML is the language of the Web, and every Web developer should have a basic understanding of it.
HTML 4.01 is an important Web standard, and very different from HTML 3.2.
When tags, like font and color attributes, were added to HTML 3.2, it started a developer's nightmare. Development of web sites where font information must be added to every single Web page is a long and expensive job.
With HTML 4.01, all formatting can be moved out of the HTML document, and into a separate style sheet.
SS - Cascading Style Sheets
Styles define how HTML elements should be displayed, just like the tag in HTML 3.2.
Style sheets are normally saved in external files. External style sheets enable you to change the appearance and layout of EVERY page in your Web site, just by editing a single document. If you have ever tried changing something like the font or color of all the headings in all your HTML pages, you will understand how CSS can save a lot of work!
XHTML
XHTML stands for Extensible HyperText Markup Language.
XHTML is a reformulation of HTML 4.01 in XML, and is supported in all major
XML - A Tool for Describing Data
XML is NOT a replacement for HTML. XML describes data, while HTML displays the data.
XML is as a cross-platform, software-, and hardware-independent tool for storing and transmitting information.
We believe that XML is as important to the Web as HTML was to the foundation of the Web, and that XML will be the most common tool for all data manipulation and data transmission.
XSLT - A Tool for Transforming Data
XSLT is used to transform XML documents into other formats, like HTML, WML, etc.
XSLT can transform an XML file into a format that is recognized by a browser.
XSLT can also add HTML elements, rearrange and sort data, make decisions about which data to display, and more.
JavaScript - Client-Side Scripting
Client-side scripting is about "programming" the behavior of a browser.
To deliver more dynamic web content, you should teach yourself JavaScript.
• JavaScript gives HTML designers a programming tool
• JavaScript can put dynamic text into an HTML page
• JavaScript can react to events
• JavaScript can change HTML elements
• JavaScript can be used to validate data
ASP or PHP - Server-Side Scripting
Server-side scripting is about "programming" an Internet server.
To deliver more dynamic web content, you should teach yourself server-side scripting.
With server-side scripting, you can:
• Dynamically edit, change, or add any content of a Web page
• Respond to user queries and form data
• Access databases and return the result to a browser
• Access files and return the result to a browser
• Transform XML data to HTML data and return the results to a browser
• Customize a Web page to make it more useful for individual users
• Provide security and access control to Web pages
• Tailor your output to different types of browsers
• Minimize network traffic
Managing Data with SQL
SQL is the standard language for accessing and manipulating databases.
SQL is used to access and manipulate data in MySQL, SQL Server, MS Access, Oracle, Sybase, DB2, and other database systems.
Knowledge of SQL is a must for anyone wanting to store or retrieve data from a database.

What Will the Future Bring?
One important thing to know is that the functionality of Web Sites will change very drastically. We will see a huge shift from sites displaying "static content" to data driven sites delivering "dynamic content".
We will also see new browsers, like the browsers found in mobile devices. We will also see more use of XML for transmitting data between servers, or between servers and browsers.