If readers are unlikely to be familiar with a word, a phrase, or an idea important to your topic, you must explain it for them. Quoting or paraphrasing a source can help you define terms and concepts in neutral, accessible language.

The student writer of the paper on childhood obesity uses a scholarly source to explain how one of the major obesity drugs functions.

Sibutramine suppresses appetite by blocking the reuptake of the neurotransmitters serotonin and norepinephrine in the brain (Yanovski & Yanovski, 2002, p. 594).