Indirect questions are used to be more polite than direct questions. They use sentence word order and terms like "if" and "whether" for yes/no questions. Indirect questions can request information or an action. They use various introductory phrases like "Do you know...", "I wonder...", and "Could you tell me..." to politely ask for information from others, especially strangers. The document provides examples of direct questions and their indirect equivalents, as well as exercises rewriting direct questions indirectly using different introductory phrases.