Is the P Endtag Required?

W³C says of : "The end tag is optional as it can always be inferred by the parser." This means that a new  implies the end of the previous  (and any alignment set by the previous ).

Any other block level element, such as <HR ...> or <BLOCKQUOTE ...> should also end the paragraph. However, it doesn't always work out that way. Some browsers, for example, will right-align the text even after a table. In the following example, MSIE renders the "after the table" part as right aligned, while Netscape renders is as left aligned:

<P STYLE="text-align:right">
before the table

<TABLE BORDER>
<TR> <TH>Dawn</TH>   <TD>1-2028</TD> </TR>
<TR> <TH>Mary K</TH> <TD>1-4952</TD> </TR>
</TABLE>

after the table

Screen shot of MSIE's rendering of the example
MSIE's rendering Screen shot of Netscape's rendering of the example
Netscape's rendering

If you set the alignment or other style property for a paragraph element it's best to use . If you never use set any styles then you can generally ignore .

See W³C's specs for paragraphs for more information on this topic.