Why has XHTML been deemed as necessary?

Answer 1

XHTML was created to replace the old syntax system of which HTML was based off of; the Standard Generalized Markup Language (SGML). SGML was difficult for computers to read and manipulate automaticly -- therefore, a new HTML system involving XML was proposed. By conforming HTML into XML syntax, computers were able to read and manipulate standard XHTML (the new name for the combined-syntax language) with accuracy.

Answer 2

all you people answering this ? are idiots, not one of you ever answer the ? given here, the real answer for those who take this seriously is:

XHTML will offer additional possibilities to clients and make it easier on yourself too. when using other browesers and devices such as cell phones you will have more control over doc's. it will allow for a quicker responce if something goes wrong with having a solid foundation with the proper coding. XHTML = more compatibility and conformity. the code is cleaner and more self explanatory too.