Quoting is when you use someone's exact words in your research.
You might use a direct quote when you feel the author's words express the point better than you could with a summary or paraphrase. For example, if you were writing a paper on film adaptations of Harry Potter and wanted to use a direct quote from a film review online, it might look like this:
According to Manolha Dargis' New York Times film review, the Harry Potter series, "has begun to show signs of stress around the edges."
If your quote is more than four lines of prose or three lines of verse long you need to follow the rules for block quoting. In MLA style you must indent the quote one inch. Continue to use double-spacing, but you do not need to put quotation marks around the quote. The in-text citation will be the same as with short quotes. See an example here.