How is a tag in HTML used?

An HTML tag may be an opening tag, or a closing tag, if a closing tag is required for the element. An opening tag consists of an element surrounded by angle brackets, and may optionally contain attributes as well. A closing tag, if it is nessary or optional for that element, contains a back-slash before the element, to distinguish it from the opening tag.

H1, P, FORM are all elements, while <H1>, <P> and <FORM> are all tags. There is no H1 tag, only an H1 element.

Elements make up the structure of an HTML document. Attributes compliment the elements, eg: <p class="something">This paragraph as a different class attribute.</p>