Is DOCTYPE specification is necessary for an html page?

Hey friends,i've seen in many sites source code that,they use DOCTYPE codes in the beginning. So,it is necessary or mandatory for our html page? I cant understand. I've no where used such codes in my page. If its mandatory,den i'll. But b4 dat,i want some suggestions.

no you can use .htm, .html, .php, .asp i think it is and whatever else extentions there are to create websites...

Arey i'm not asking that one bro. I just want to ask that,is it necessary to give the header code in a html page with its introduction like DOCTYPE UNI8 TEXT TYPE HTML,etc. Dont think,its the tag. I've just given a example.

The DOCTYPE tag is necessary for giving other crawlers an idea what is your file's format. There are different Markup Languages around and the first line tag ( DOCTYPE ) points to the DTD reference file which gives the descriptions for each tags you used on the page. That helps you to get better positions on search engines.

Does dis tag create any problem with the different kind of browsers which my visitors from worldwide use? Because,i hear sometimes that,some ppl face problem to access my main page. Cant understand why.

Normally browsers have DTD for all HTML tags. But some browsers show errors if the HTML pages don't have the Document type specifications. But in my experience, I never received any complaints because of doctype specification.

doctype tags not so necessory for the working of html pages except that with crawlers
but in the case of wml language or wap pages must use doc introduction before starting language,
else they wont appear

That is because in default, it normally check the extension of the file. If it is an HTML file, it is consider as an HTML page. If you are using an XHTML page or pages with some other DTD format like WML ( Used for WAP pages ), you should explain the DOCTYPE of file.

yup thats what i said bro,also i think some hosts wont allow to host wml
Also what this DOC type indicates,and also i saw a tag in all wml pages that is starting with a wap address like wapforum or wap school
what that means

DOCTYPE just indicating the type of Markup Language for the Document. You can see a good tutorial about WAP Site creation of here: http://webmasters-forums.com/Tutorial-Fo...t-864.html

sorry completely missunderstood the question, was very tired that day lol....didn't read question right..

I'm saying about the header commententary in which the type is specified,which counts for validation.