A long quote (often referred to as a block quote) is a special paragraph that is used for including a quote to another source that is generally more than 3 lines long. Quotes that are smaller than this, should be contained in the paragraph. This special paragraph can be styled different to a paragraph, often by indenting it and using a smaller font size. This 'highlights' the quote; that is, makes it stand out.
Tips
The reference to your quote can be added into the paragraph text above, or into the long quote object (usually at the end).
Consult your official style guide to find out what the Style requirements are for long quotes.