A topic is the one thing the whole paragraph is about. It is the unifying factor, which every sentence and idea contained in the paragraph relate to. To find the topic of a paragraph, ask yourself this question: "Which person, event, practice, theory, or idea is most frequently mentioned or referred to in the paragraph?" Usually, the topic of a paragraph can be expressed in one word or a phrase consisting of two or more words. That's why a topic could also be defined as the word or phrase that best describes what all of the sentences in the paragraph are about.