About the Tag

It is obligatory (Mandatory) to use the <P> tag for writing a paragraph in a HTML document, or I can use other than <p> tag for writing a paragraph like <t>?
And does this new <t> tag is Search Engine (like "Google") friendly or W3C (World Wide Web Consortium) friendly (for paragraph writing), or it may lead to problems? :confused:

(X)HTML has a predefined set of elements and you can’t make up your own ones (well you can but don’t wonder if the browsers don’t play along nicely). If you want custom elements you have to look into real XML. But that’s not primarily made for websites and not supported in all browsers (talk about IE?).