Indirect questions are more polite than direct questions, especially when speaking to strangers. To form an indirect question, use an introductory phrase followed by the question in a positive or negative structure connected by a question word like "who", "where", or "if/whether". Common introductory phrases include "Do you know...", "Can/Could you tell me...", and "May I ask you...". Indirect questions serve the same purpose as direct questions but are considered more formal.