Deixis refers to words and phrases that require contextual information to convey meaning. These expressions, such as this, that, here, and there, depend on the speaker's perspective and the situation in which they are used. Deictic expressions help listeners understand who is speaking, where the conversation is taking place, and when events occur. There are several types of deixis, including person deixis, which indicates the speaker and listener, time deixis, which refers to when something happens, and place deixis, which specifies locations. Understanding deixis is essential for effective communication, as it clarifies references and relationships in conversation.