Ordered list. The HTML <ol> tag is used for define an ordered list.
Ordered lists are often numbered (1. 2. 3... etc), however, they don't necessarily have to be. The main point of an ordered list is that the list items have been ordered, such that changing the order would change the meaning of the list (or document).
This element is used in conjunction with the <li> element. The <ol> tag declares the ordered list, and the <li> tag declares each list item.
<ol> <li>First List Item</li> <li>Second List Item</li> <li>Third List Item</li> </ol>