HTML List

A simple list division in the HTML document can be defined by a <ul> element or a <ol> element. An unordered list is created and enclosed by open tag <ul> and end tag </ul>. An ordered list is created and enclosed by open tag <ol> and end tag <ol>.

A more complex definition list division in the HTML document can also be defined by a <dl> element. A definition list is created and enclosed by open tag <dl> and end tag </dl>.

Besides, there are also two deprecated elements, <dir> and <menu> to define  directory listing and menu listing. An directory list is created and enclosed by open tag <dir> and end tag </dir>. An menu list is created and enclosed by open tag <menu> and end tag </menu>.

List item <li> in unordered list <ul> and ordered list <ol>

A nested <li> element is used to define a list item in the list. The list content is held between the open tag <li> and the optional end tag </li>. List items are rendered as bulleted items in a unordered list <ul>. And list items are rendered as numbered items in a ordered list.

List of term <dt> and definition <dd> in definition list <dl>

A nested <dt> element is first used to define the "term" of a list item in the list. The "term" is held between the open tag <dt> and the optional end tag </dt>. Then a nested <dd> element is used to define the "description" of a list item in the list. The "description" is held between the open tag <dt> and the optional end tag </dt>.
The "term" of the definition list items are rendered in a left column of the definition list. And  the "description" of the definition items are rendered in a right column of the definition list with a wider left indent. Besides the text content of <dt> element is restricted to inline content. While  the text content of <dd> element can be block-level content.

List item <li> in directory list <dir> and menu list <menu>

The <dir> element and <menu> element are deprecated elements
A nested <li> element is also used to define a list item in the directory list <dir> and menu list <menu>. The list content is held between the open tag <li> and the optional end tag </li>. List items in directory list <dir> and menu list <menu> are rendered as bulleted items as in a unordered list <ul>.

Nested list

Different types of list can be nested together. The nested list is enclosed inside the corresponding list item element.