There are several online forums and communities where you can discuss doubts related to the UPSC (Union Public Service Commission) exam preparation. These platforms provide a space for aspirants to connect with each other, seek guidance, and share valuable insights. Here are a few popular ones:

1. EduRev: EduRev is a comprehensive educational platform that offers a dedicated section for UPSC preparation. It provides a forum where students can post their doubts, engage in discussions, and receive answers from fellow aspirants and experts.

2. Quora: Quora is a popular question-and-answer platform where you can find a wide range of topics, including UPSC preparation. Many UPSC aspirants actively participate in discussions on Quora, providing detailed answers to doubts and sharing their experiences.

3. ClearIAS Forum: ClearIAS is a trusted online platform that offers guidance and resources for UPSC exam preparation. They have a dedicated forum where aspirants can ask questions, seek clarifications, and interact with experts and fellow UPSC candidates.

4. UPSC Forums on Gradeup: Gradeup is a well-known platform for exam preparation, and it hosts dedicated forums for various competitive exams, including UPSC. These forums allow aspirants to post their doubts and receive responses from experts and peers.

5. ForumIAS: ForumIAS is a popular online community exclusively focused on UPSC exam preparation. It provides a platform where aspirants can discuss doubts, share strategies, and seek guidance from experienced mentors.

Key Points:
- EduRev, Quora, ClearIAS Forum, Gradeup, and ForumIAS are popular online platforms for discussing UPSC-related doubts.
- These forums enable aspirants to connect with experts and peers, seek clarifications, and share insights.
- EduRev, in particular, has a dedicated section for UPSC preparation and offers a comprehensive platform for doubt resolution.
- Quora is a widely used question-and-answer platform where you can find discussions on various UPSC-related topics.
- ClearIAS, Gradeup, and ForumIAS also provide forums specifically designed for UPSC exam preparation.