Blockquote

The HTML   element indicates that the enclosed text is an extended quotation. Usually, this is rendered visually by using indents. The source of the quotation may also be stated using the HTML  element.

Attributes

 * - The value of this attribute is a URL that designates a source document or message for the information quoted. This attribute is intended to point to information explaining the context or the reference for the quote.

To apply this in HTML, use:

The HTML & CSS Wiki is a large database containing lots of information.

That produces:

"The HTML & CSS Wiki is a large database containing lots of information."

Rendering
The element is rendered as a block with a margin on all four sides.

Notable exceptions
Firefox:
 * Blockquotes of type "cite" are rendered with a blue line on the left side. (Or on the right side, for right-to-left reading languages.)

HTML5 Categories

 * Flow content
 * Sectioning root