The <blockquote> tag is used for indenting text about half an inch in from both the left and right margins of the edges of the user's browser. While it is certainly useful for quotes (which are generally indented from the regular text), this tag can be used in other ways as well.

Here is an example of three <blockquote> tags that have been strung together to force a much larger indentation from the left and right sides of the browser window. Notice how ending a <blockquote> tag inserts the equivalent of two <br> tags.