What are the <ol>, <ul>, and <li> tags used for in HTML?

The tags <ol>, <ul>, and <li> are used to create lists in HTML:

• <ol> (Ordered List) - creates an ordered (numbered) list. List items are automatically numbered (with numbers, letters, etc., by default or as specified by the type).
• <ul> (Unordered List) - creates an unordered (bulleted) list. List items are marked with bullets (dots, squares, circles by default or as specified by the type).
• <li> (List Item) - defines a single list item. This tag must be inside <ol> or <ul> tags.

Example:

<!-- Unordered list -->
<ul>
  <li>First item</li>
  <li>Second item</li>
  <li>Third item</li>
</ul>

<!-- Ordered list -->
<ol>
  <li>First item</li>
  <li>Second item</li>
  <li>Third item</li>
</ol>