There are two main, significant problems with HTML that led to the development of XHTML. Explain both of these.

What will be an ideal response?

One problem that developers confronted early on in the history of HTML was that Web browsers supported their own unique flavors of HTML in order to provide customers with new and useful features not available with other browsers. For example, the iframe element was originally introduced in the Internet Explorer browser as a way of embedding the contents of one page within another. Although this extension was later adopted into the official HTML specifications by the World Wide Web Consortium (W3C), many other extensions were not adopted-such as Internet Explorer's marquee element, which was used to create blocks of scrolling text. The opposite is also true: Some specifications proposed by the W3C are adopted by only a few browsers. The result was a confusing mixture of competing HTML standards-one kind of HTML for each browser and, even worse, for each browser version. Although browser-specific elements and attributes increased the scope and power of HTML, they did so at the expense of clarity. Web designers could no longer create Web sites without taking a lot of time and effort to ensure their sites worked across various browsers and browser versions.

Another issue that complicated the development of HTML was that browsers allowed page authors to be lax in their use of syntax. For example, the following code does not follow HTML specifications because the h1 element has not been closed with an ending tag:

ƒƒƒ

WebƒPageƒTitle

HTML 647
Although this code does not follow the correct syntax, most browsers still render it correctly. Likewise, the following code would likely be interpreted correctly even though the colspan attribute value is not enclosed in quotation marks:
Heading

Although a browser that is very forgiving of mistakes in syntax might seem beneficial to Web page designers, this behavior also affects the browser design. By making allowances for inconsistently applied HTML code, the source code for the browser itself must be larger and more complex to deal with all contingencies. This can become an issue for browsers that run on handheld devices, which are more limited in the space they allot for software. Because of these concerns, several developers began to push for a version of HTML in which syntax rules would be more strictly enforced. This was done by making HTML into an XML vocabulary.

Computer Science & Information Technology