What Is a Topic? In order to understand what you are reading,you need to connect it to something you already know.To make this connection, you need to be sure that you know what it is that you are reading about. That is, you need to know the topic. What is a topic? The topic is the main thought or subject of a paragraph, book, or research paper etc. that is under discussion. In short, it is a word or phrase (a few words) that tells us what something is about. It expresses the general idea and is often stated in a word or phrase, to which the ideas of a passage as a whole belong. To find the topic of a reading ask yourself, "What or who is the reading about?" The answer will be the topic. You should always look for the topic when you read.