Quoting is where you copy an author's text word for word, place quotation marks around the words and add a citation at the end of the quote, including the page number where the quote can be found.
Quotes should be used sparingly as over-quoting can suggest a lack of understanding of the text you are referring to.
In scientific writing, you are generally expected to paraphrase from sources, rather than quote directly. Quoting more extended sections of text is more common in arts and humanities subjects, where it may be appropriate to quote frequently from the literature that is being analysed.
As you take notes, ensure you clearly mark where you have quoted directly from the source.