please diferent between html and xhtml?

MIME Types XHTML must be served with an XML MIME type, such as application/xml or application/xhtml+xml. HTML must be served as text/html. It is the MIME type that determines what type of document you are using. If you use attempt to send XHTML as text/html, you are actually just using HTML, possibly with syntax errors. Technically, according to the spec, XHTML 1.0 is allowed to be served as text/html. But, due to the above reason, such a document is considered to be an HTML document, not an XHTML documen

The history of HTML at W3C starts with HTML 3.2, code named Wilbur, which was followed a few years later by HTML 4.0, then HTML 4.01. HTML 4.01 is the last version of HTML, and is also the final W3C specification to define the semantics of markup. From HTML 3.2 to HTML 4.01, the language has improved a great deal, focusing on such issues as: Separation of presentation from structure Improved accessibility features Improve internationalization features Improved document rendering XHTML 1.0 was created shortly after HTML 4.01 to help the transition of hypertext to a new generation of mark-up languages for text. XHTML 1.1 is an additional step toward a more flexible version of hypertext with the full benefits of XML architecture and integration of different technologies. Note that XHTML 1.1 has slighly improved the semantics of HTML 4.01 by including the Ruby module, used in particular languages like Japanese scripts (read the Ruby Specification for more information). For practical purposes, the discussion here will focus on HTML 4.01 and XHTML 1.0

The best language you can learn is XHTML! Why not HTML? HTML is getting really old fashioned! The biggest difference is that XHTML removes al the 'design tags'. When you learn XHTML you will have to learn CSS too :-). You will use XHTML for the content and CSS for the design. This will keep those 2 seperate. HTML still uses design tags. Nowadays it is not really used a lot anymore. Hope it is more clear now! :-) Have fun! Tine

HTML is Hypertext Mark-up language. XHTML is a stricter, cleaner version of HTML. You can go to www.w3schools.com to learn about them both.

Differences Between HTML and XHTML Please note that the information in here is based upon the current spec for (X)HTML5. Some of the issues technically do not apply to previous versions of HTML. Although HTML and XHTML appear to have similarities in their syntax, they are significantly different in many ways. Note: As the current WHATWG document is a draft, this section will need to track to a moving target. Differences marked @@@ are differences that could theoretically be changed without affecting I am writing more backwards compatibility.

great answer Harendrakumarkiran, well to make long things short I will say that XHTML is the next generation of HTML itself, the idea is to turn HTML to a more strict semantic and to make it compatible with XML in order to make documents with more than one language like XML+SVG or XML+MathML, XHTML1.0 is the bridge between HTML and XHMTL is meant to be compatible with both, so old HTML browsers can read this documents and at the same time being XHTML compilant (this is, well written according to the standards). now, as XHTML *is* HTML you will need to know HTML too! in particular because the XHTML1.0 spec does not make a very profound description of it's markup instead it show a comparative chart against HTML, so if you're learning do HTML but stick to that chart in order to do XHTML from the beggining, the HTML4.01 spec is here: http://www.w3.org/TR/html401/ and the XHTML1.0 here: http://www.w3.org/TR/xhtml1/ (you should browse the entire w3 site, there are lots of interesting thing around there) you've asked about SEO also, (SEO = Search Engine Optimization) this is a topic of it's own and has lots of different aspects but yes, it is said that good markup helps reanching higher positions