This description may be completely modified. You can use here all html tags like: bold text, underline, italics and much more. If you're wondering what is possible check out this link.

"The HTML blockquote Element (or HTML Block Quotation Element) indicates that the enclosed text is an extended quotation. Usually, this is rendered visually by indentation (see Notes for how to change it). A URL for the source of the quotation may be given using the cite attribute, while a text representation of the source can be given using the cite element."