The majority of HTML tags belong to a container tag set. A container tag set consists of a start tag delimited by "<" and ">" and an end tag, delimited by "</" and ">." In some cases, the end tag is optional.
<ELE [ATTRIB1[="val1"]] [ATTRIB2[="val2"]] ... [ATTRIBx[="valx"]]>
Content
</ELE>
<FORM ACTION="url.cgi" METHOD=post> ... </FORM>
Forms make use of a container tag set in which both the start and end tags are required.