Introduction is the opening of a presentation, speech, or piece of writing that introduces the topic and provides the audience with a general overview of the material that will be discussed or written about. There are two main types of introduction: formal and informal. A formal introduction is typically used in academic or professional settings and is often more formal and structured than an informal one. Formal introductions usually begin with a statement of the purpose of the presentation, followed by a brief summary of the main points to be discussed. An informal introduction is typically used in more casual settings and is often less structured than a formal one. Informal introductions may begin with a joke, anecdote, or other humorous element, or they may simply provide a few facts and an overview of the topic.