Which HTML tag is used to define an unordered list?

The HTML tag used to define an unordered list is "ul." This tag signifies that the contained items are part of a list where the order does not matter, making it distinct from an ordered list, which is defined using the "ol" tag. When an unordered list is created using the "ul" tag, the list items are typically represented with bullet points by default, enhancing the visual clarity of the list.

In contrast, the "ol" tag is used specifically for ordered lists, where the sequence of items is important and is typically represented with numbered items. The "p" tag is used for paragraphs, serving a completely different purpose in formatting text content. The "div" tag is a block-level container used for grouping content and does not provide any specific meaning related to lists. Therefore, the "ul" tag is the correct choice for indicating an unordered list in HTML.